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These records are all the terms and abbreviations in my Glossary Of Terms database:

Acronym	Description
2.5G	2.5G describes the state of wireless technology and capability usually associated with General Packet Radio Services (GPRS) - that is, between the second and third generations of wireless technology. The second generation or 2G-level of wireless is usually identified as Global System for Mobile (GSM) service and the third generation or 3G-level is usually identified as Universal Mobile Telecommunication Service (UMTS). Each generation provides a higher data rate and additional capabilities. There is also a fourth generation (4G) of technology in the planning and research stages. GPRS offers data speeds at 28 Kbps (and possibly higher) and is expected to be introduced in the 2001 through 2003 timeframe.
3G	3G is a short term for third-generation wireless, and refers to near-future developments in personal and business wireless technology, especially mobile communications. This phase is expected to reach maturity between the years 2003 and 2005. The third generation, as its name suggests, follows the first generation (1G) and second generation (2G) in wireless communications. The 1G period began in the late 1970s and lasted through the 1980s. These systems featured the first true mobile phone systems, known at first as "cellular mobile radio telephone." These networks used analog voice signaling, and were little more sophisticated than repeater networks used by amateur radio operators. The 2G phase began in the 1990s, and much of this technology is still in use. The 2G cell phone features digital voice encoding. Examples include CDMA, TDMA, and GSM. Since its inception, 2G technology has steadily improved, with increased bandwidth, packet routing, and the introduction of multimedia. The present state of mobile wireless communications is often called 2.5G. While 3G is generally considered applicable mainly to mobile wireless, it is also relevant to fixed wireless and portable wireless. The ultimate 3G system might be operational from any location on, or over, the earth's surface, including use in homes, businesses, government offices, medical establishments, the military, personal and commercial land vehicles, private and commercial watercraft and marine craft, private and commercial aircraft (except where passenger use restrictions apply), portable (pedestrians, hikers, cyclists, campers), and space stations and spacecraft. Proponents of 3G technology promise that it will "keep people connected at all times and in all places." Researchers, engineers, and marketeers are faced with the challenge of accurately predicting how much technology consumers will actually be willing to pay for. (Recent trends suggest that people sometimes prefer to be disconnected, especially when on vacation.) Another concern involves privacy and security issues. As technology becomes more sophisticated and bandwidth increases, systems become increasingly vulnerable to attack by malicious hackers (known as crackers) unless countermeasures are implemented to protect against such activity.
802.11	802.11 is a family of specifications for wireless local area networks (WLANs) developed by a working group of the Institute of Electrical and Electronics Engineers (IEEE). There are currently four specifications in the family: 802.11, 802.11a, 802.11b, and 802.11g. All four use the Ethernet protocol and CSMA/CA (carrier sense multiple access with collision avoidance) for path sharing. The most recently approved standard, 802.11g, offers wireless transmission over relatively short distances at up to 54 megabits per second (Mbps) compared with the 11 megabits per second of the 802.11b standard. Like 802.11b, 802.11g operates in the 2.4 GHz range and is thus compatible with it. The 802.11b standard - often called Wi-Fi - is backward compatible with 802.11. The modulation used in 802.11 has historically been phase-shift keying (PSK). The modulation method selected for 802.11b is known as complementary code keying (CCK), which allows higher data speeds and is less susceptible to multipath-propagation interference. The 802.11a specification applies to wireless ATM systems and is used in access hubs. 802.11a operates at radio frequencies between 5 GHz and 6 GHz. It uses a modulation scheme known as orthogonal frequency-division multiplexing (OFDM) that makes possible data speeds as high as 54 Mbps, but most commonly, communications takes place at 6 Mbps, 12 Mbps, or 24 Mbps.
802.11b	Wi-Fi is the popular term for a high-frequency wireless local area network (WLAN). The Wi-Fi technology is rapidly gaining acceptance in many companies as an alternative to a wired LAN. It can also be installed for a home network. Wi-Fi is specified in the 802.11b specification from the Institute of Electrical and Electronics Engineers (IEEE) and is part of a series of wireless specifications together with 802.11, 802.11a, and 802.11g. All four standards use the Ethernet protocol and CSMA/CA (carrier sense multiple access with collision avoidance) for path sharing. The 802.11b (Wi-Fi) operates in the 2.4 GHz range offering data speeds up to 11 megabits per second. The modulation used in 802.11 has historically been phase-shift keying (PSK). The modulation method selected for 802.11b is known as complementary code keying (CCK), which allows higher data speeds and is less susceptible to multipath-propagation interference. Unless adequately protected, a Wi-Fi wireless LAN can be susceptible to access from the outside by unauthorized users, some of whom have used the access as a free Internet connection! (The activity of locating and exploiting security-exposed wireless LANs is commonly known as war driving.) Companies that have a wireless LAN are urged to add security safeguards such as the Wired Equivalent Privacy (WEP) encryption standard, the setup and use of a virtual private network (VPN) or IPsec, and a firewall or DMZ.
802.15	802.15 is a communications specification that was approved in early 2002 by the Institute of Electrical and Electronics Engineers Standards Association (IEEE-SA) for wireless personal area networks (WPANs). The initial version, 802.15.1, was adapted from the Bluetooth specification and is fully compatible with Bluetooth 1.1. Bluetooth is a well-known and widely used specification that defines parameters for wireless communications among portable digital devices including notebook computers, peripherals, cellular telephones, beepers, and consumer electronic devices. The specification also allows for connection to the Internet. The IEEE 802.15 Working Group proposes two general categories of 802.15, called TG4 (low rate) and TG3 (high rate). The TG4 version provides data speeds of 20 Kbps or 250 Kbps. The TG3 version supports data speeds ranging from 11 Mbps to 55 Mbps. Additional features include the use of up to 254 network devices, dynamic device addressing, support for devices in which latency is critical, full handshaking, security provisions, and power management. There will be 16 channels in the 2.4-GHz band, 10 channels in the 915-MHz band, and one channel in the 868-MHz band. The IEEE plans to refine the 802.15 specification to work with the Specification and Description Language (SDL), particularly SDL-88, SDL-92, and SDL-2000 updates of the International Telecommunication Union (ITU) recommendation Z.100.
802.1X	The 802.1X standard is designed to enhance the security of wireless local area networks (WLANs) that follow the IEEE 802.11 standard. 802.1X provides an authentication framework for wireless LANs, allowing a user to be authenticated by a central authority. The actual algorithm that is used to determine whether a user is authentic is left open and multiple algorithms are possible. 802.1X uses an existing protocol, the Extensible Authentication Protocol (EAP, RFC 2284), that works on Ethernet, token ring, or wireless LANs, for message exchange during the authentication process. In a wireless LAN with 802.1X, a user (known as the supplicant) requests access to an access point (known as the authenticator). The access point forces the user (actually, the user's client software) into an unauthorized state that allows the client to send only an EAP start message. The access point returns an EAP message requesting the user's identity. The client returns the identity, which is then forwarded by the access point to the authentication server, which uses an algorithm to authenticate the user and then returns an accept or reject message back to the access point. Assuming an accept was received, the access point changes the client's state to authorized and normal traffic can now take place. The authentication server may use the Remote Authentication Dial-In User Service (RADIUS), although 802.1X does not specify it.
access number	The telephone number used by a subscriber to dial into an Internet Service Provider or online service.
ACK	2 Meanings: 1. Acknowledge. Used to confirm one's presence. An appropriate response to ping. 2. When one computer sends a block of data to another over a network, the second computer sends an acknowledgment code back to indicate that the transfer was successful. If there were errors detected in the transmission, the second computer would send a negative acknowledgment (NAK).
Active X	A software technology developed by Microsoft that allows programmed capabilities or content to be delivered to Windows-based personal computers via the World Wide Web. Active X is notable for a complete lack of security controls; computer security experts discourage its use over the Internet.
address	There are three types of addresses in common use on the Internet: email addresses, IP addresses, and Uniform Resource Locators. See also email address, IP address, Uniform Resource Locator.
address book	A feature of some email applications that stores names and email addresses in an accessible format.
ADN	Advanced Digital Network Usually refers to a 56Kbps leased-line.
ADPCM	Adaptive Differential Pulse Code Modulation A form of pulse code modulation (PCM) that produces a digital signal with a lower bit rate than standard PCM. ADPCM produces a lower bit rate by recording only the difference between samples and adjusting the coding scale dynamically to accommodate large and small differences. Some applications use ADPCM to digitize a voice signal so voice and data can be transmitted simultaneously over a digital facility normally used only for one or the other.
ADSL	Asymmetric Digital Subscriber Line A DSL line where the upload speed is different from the download speed. usually the download speed is much greater.
AFK	Away From Keyboard
agent	A software process empowered to transparently act for or represent a user by completing transactions, seeking information of specific interest, or communicating with other users and agents. The Firefly online service is a good example of agent technology at work, http://www.firefly.com
AI	Artificial Intelligence A branch of computer science that studies how to endow computers with capabilities of human intelligence. For example, speech recognition is a problem being worked on by AI scientists.
air interface	In cellular telephone communications, the air interface is the radio-frequency portion of the circuit between the cellular phone set or wireless modem (usually portable or mobile) and the active base station. As a subscriber moves from one cell to another in the system, the active base station changes periodically. Each changeover is known as a handoff. A cellular connection is only as good as its weakest link, which is almost always the air interface. Radio-frequency (RF)circuits are subject to many variables that affect signal quality. Factors that can cause problems include: - Use of the handheld phone set or portable wireless modem inside buildings, cars, buses, trucks, or trains - Proximity to human-made, steel-frame obstructions, especially large buildings and freeway overpasses - Abundance of utility wires that can reflect radio signals and/or generate noise that interferes with reception - Irregular terrain, particularly canyons and ravines - Inadequate transmitter power in phone set or wireless modem - Poorly designed antenna in phone set or wireless modem In addition to these variables, some cellular networks have inadequate coverage in certain geographic areas. Usually this is because there are not enough base stations to ensure continuous communications for subscribers using portable (handheld) phone sets. As a network evolves, more base stations may be installed in a given region, and in that case, this problem will diminish with time. Conversion of a network from analog to digital can result in dramatic improvement.
alt	2 meanings: 1. A top-level category of "alternative" USENET newsgroups. These unmoderated newsgroups can be started by anyone with the time, equipment, and expertise. The alt hierarchy covers perhaps the widest variety of topics ranging from the informative to the bizarre, and from the politically radical to the explicitly sexual. 2.The Alt key on the keyboard of IBM PC compatibles, typically used in conjunction with other keys.
anonymous FTP	A service that allows free public access to archived documents, files, and programs via the File Transfer Protocol (FTP). It's not necessary to have a user ID and password when logging into an anonymous FTP site. The user ID "anonymous" bypasses local security checks; often email addresses serve as courtesy passwords. See also File Transfer Protocol.
API	Application Program Interface A document for programmers that provides the technical specifications for interfacing with an application from another program.
Applet	A small Java program that can be embedded in an HTML page. Applets differ from full-fledged Java applications in that they are not allowed to access certain resources on the local computer, such as files and serial devices (modems, printers, etc.), and are prohibited from communicating with most other computers across a network. The common rule is that an applet can only make an Internet connection to the computer from which the applet was sent.
application	A self-contained program that performs a well-defined set of tasks under user control, as opposed to a system program. Web browsers, mail readers, and FTP clients are examples of applications commonly used on the Internet.
Archie	A tool (software) for finding files stored on anonymous FTP sites. You need to know the exact file name or a substring of it. By 1999 Archie had been almost completely replaced by web-based search engines. back when FTP was the main way people moved files over the Internet archie was quite popular.
archive site	A server that provides access to an organized collection of files available to the public.
ARPANet	Advanced Research Projects Agency Network The precursor to the Internet. Developed in the late 60's and early 70's by the US Department of Defense as an experiment in wide-area-networking to connect together computers that were each running different system so that people at one location could use computing resources from another location.
ASCII	American Standard Code for Information Interchange This is the defacto world-wide standard for the code numbers used by computers to represent all the upper and lower-case Latin letters, numbers, punctuation, etc. There are 128 standard ASCII codes each of which can be represented by a 7 digit binary number: 0000000 through 1111111.
asynchronous	Not synchronized; that is, not occurring at predetermined or regular intervals. The term asynchronous is usually used to describe communications in which data can be transmitted intermittently rather than in a steady stream. For example, a telephone conversation is asynchronous because both parties can talk whenever they like. If the communication were synchronous, each party would be required to wait a specified interval before speaking. The difficulty with asynchronous communications is that the receiver must have a way to distinguish between valid data and noise. In computer communications, this is usually accomplished through a special start bit and stop bit at the beginning and end of each piece of data. For this reason, asynchronous communication is sometimes called start-stop transmission. Most communications between computers and devices are asynchronous.
AT command set	Pronounced ay-tee command set, the de facto standard language for controlling modems. The AT command set was developed by Hayes and is recognized by virtually all personal computer modems.
attachment	A file that is embedded into an email message.
AUP	Acceptable Use Policy A formal set of rules that governs how a network may be used. For example, the original NSFnet Acceptable Use Policy forbade non-research use by commercial organizations. AUPs sometimes restrict the type of material that can be made publicly available; many AUPs ban the transmission of pornographic material.
authentication	The verification of the identity of a person or process.
Backbone	A high-speed line or series of connections that forms a major pathway within a network. The term is relative as a backbone in a small network will likely be much smaller than many non-backbone lines in a large network. The top level of a hierarchical network. The main pipes along which data is transferred. The "Internet backbone" is sometimes referred to, though it doesn't exist.
Bandwidth	2 Meanings: 1. The amount of information or data that can be sent over a network connection in a given period of time. Bandwidth is usually stated in bits per second (bps), kilobits per second (kbps), or megabits per second (mps). 2. The technical meaning is generalized in hacker slang. Individuals are said to be "high bandwidth" if they are able to process large volumes of information in short periods of time.
BASIC	Beginners All-purpose Symbolic Instructional Code An easy-to-learn, highly flexible computer language invented at Dartmouth University. Different versions of BASIC run on various operating systems. Since each version has its own peculiar quirks, a BASIC program written in one version may not be compatible with another version.
Baud	The speed of a modem. Specifically, the number of times per second a communications channel changes the carrier signal it sends on the phone line. A 2400-baud modem changes the signal 2400 times a second. Baud is often confused with bits per second (bps). They are technically different measurements.
BBS	Bulletin Board System A computerized meeting and announcement system that allows people to carry on discussions, upload and download files, and make announcements without the people being connected to the computer at the same time. In the early 1990's there were many thousands (millions?) of BBS?s around the world, most are very small, running on a single IBM clone PC with 1 or 2 phone lines. Some are very large and the line between a BBS and a system like AOL gets crossed at some point, but it is not clearly drawn.
bcc	Blind Carbon Copy To bcc: an email message to someone is to send them a copy of the email message without the knowledge of the person to whom the email message is addressed to.
BER	bit error rate In a digital transmission, BER is the percentage of bits with errors divided by the total number of bits that have been transmitted, received or processed over a given time period. The rate is typically expressed as 10 to the negative power. For example, four erroneous bits out of 100,000 bits transmitted would be expressed as 4 x 10^-5, or the expression 3 x 10^-6 would indicate that three bits were in error out of 1,000,000 transmitted. BER is the digital equivalent to signal-to-noise ratio in an analogue system.
BERT	Short for bit error rate test, or tester, a procedure or device that measures the bit error rate of a transmission.
beta	A version of an application that is made available prior to the official release for the purposes of testing.
Binary	Information consisting entirely of ones and zeros. Also, commonly used to refer to files that are not simply text files, e.g. images. Mathematical base 2, or numbers composed of a series of zeros and ones. Since zero's and one's can be easily represented by two voltage levels on an electronic device, the binary number system is widely used in digital computing.
Binhex	BINary HEXadecimal A method for converting non-text files (non-ASCII) into ASCII. This is needed because Internet e-mail can only handle ASCII.
BIOS	Basic Input/Output System The BIOS is built-in software that determines what a computer can do without accessing programs from a disk. On PCs, the BIOS contains all the code required to control the keyboard, display screen, disk drives, serial communications, and a number of miscellaneous functions. The BIOS is typically placed in a ROM chip that comes with the computer (it is often called a ROM BIOS). This ensures that the BIOS will always be available and will not be damaged by disk failures. It also makes it possible for a computer to boot itself. Because RAM is faster than ROM, though, many computer manufacturers design systems so that the BIOS is copied from ROM to RAM each time the computer is booted. This is known as shadowing. Many modern PCs have a flash BIOS, which means that the BIOS has been recorded on a flash memory chip, which can be updated if necessary. The PC BIOS is fairly standardized, so all PCs are similar at this level (although there are different BIOS versions). Additional DOS functions are usually added through software modules. This means you can upgrade to a newer version of DOS without changing the BIOS. PC BIOSes that can handle Plug-and-Play (PnP) devices are known as PnP BIOSes, or PnP-aware BIOSes. These BIOSes are always implemented with flash memory rather than ROM.
bisync	binary synchronous A type of synchronous communications used primarily in mainframe networks. The de facto bisync standard is Binary Synchronous Communications (BSC) developed by IBM. The binary part of the name signifies that the data is binary-coded. The synchronous part means that both the sender and receiver must be synchronized before the data transfer can begin.
Bit	Binary DigIT A single digit number in base-2, in other words, either a 1 or a zero. The smallest unit of computerized data. A bit is either on or off and is represented by "1" or "0". A collection of bits are put together to form a byte. Bandwidth is usually measured in bits-per-second.
bit stuffing	The practice of adding bits to a stream of data. Bit stuffing is required by many network and communications protocols for the following reasons: - To prevent data being interpreted as control information. For example, many frame-based protocols, such as X.25, signal the beginning and end of a frame with six consecutive 1 bits. Therefore, if the actual data being transmitted has six 1 bits in a row, a zero is inserted after the first 5 so that the dat is not interpreted as a frame delimiter. Of course, on the receiving end, the stuffed bits must be discarded. -For protocols that require a fixed-size frame, bits are sometimes inserted to make the frame size equal to this set size. - For protocols that required a continuous stream of data, zero bits are sometimes inserted to ensure that the stream is not broken.
BITNET	Because It's Time NETwork (or Because It's There NETwork) A network of educational sites separate from the Internet, but e-mail is freely exchanged between BITNET and the Internet. Listservs®, a popular form of e-mail discussion groups, originated on BITNET. BITNET machines are usually mainframes running the VMS operating system, and the network is probably the only international network that is shrinking.
Bluetooth	Bluetooth is a computing and telecommunications industry specification that describes how mobile phones, computers, and personal digital assistants (PDAs) can easily interconnect with each other and with home and business phones and computers using a short-range wireless connection. Using this technology, users of cellular phones, pagers, and personal digital assistants such as the PalmPilot will be able to buy a three-in-one phone that can double as a portable phone at home or in the office, get quickly synchronized with information in a desktop or notebook computer, initiate the sending or receiving of a fax, initiate a print-out, and, in general, have all mobile and fixed computer devices be totally coordinated. Bluetooth requires that a low-cost transceiver chip be included in each device. The tranceiver transmits and receives in a previously unused frequency band of 2.45 GHz that is available globally (with some variation of bandwidth in different countries). In addition to data, up to three voice channels are available. Each device has a unique 48-bit address from the IEEE 802 standard. Connections can be point-to-point or multipoint. The maximum range is 10 meters. Data can be exchanged at a rate of 1 megabit per second (up to 2 Mbps in the second generation of the technology). A frequency hop scheme allows devices to communicate even in areas with a great deal of electromagnetic interference. Built-in encryption and verification is provided.
bookmark	A routine that allows you to save a reference to a site or page that you have already visited. At a later point in time, you can use a bookmark to return to that page. It commonly refers to a feature of Netscape Navigator (a web browser) that allows you to collect and organize bookmarks of your favorite web sites.
boot	To start up or reset a computer. When a computer is booted, a bootstrap routine is automatically executed that looks for and loads the operating system. A cold boot is when the computer is powered up from an off state. A warm boot occurs when an already turned on computer is rebooted.
bounce	The return of a piece of email because it could not be delivered to the specified address. See also bounce message.
bounce message	A notification message returned to sender indicating that an email message could not be delivered. Usually the message is automatically generated by the Postmaster at the recipient's site, sometimes with an indication of what went wrong. The most common problem is an incorrect address, but sometimes email sent via the Internet fails for no apparent reason.
bozo filter	A feature of some email and newsgroup reader applications that screens out incoming messages from those whose correspondence is not valued.
bps	Bits-Per-Second Abbreviation for bits per second. A measurement of the number of bits of information that can be sent over a network connection. See also bandwidth. A 56K modem can move about 57,000 bits per second.
bps	bits per second The standard measure of data transmission speeds
BREW	Binary Runtime Environment for Wireless. BREW is Qualcomm's open source application development platform for wireless devices equipped for code division multiple access (CDMA) technology. BREW makes it possible for developers to create portable applications that will work on any handsets equipped with CDMA chipsets. Because BREW runs in between the application and the chip operating system software, the application can use the device's functionality without the developer needing to code to the system interface or even having to understand wireless applications. Users can download applications - such as text chat, enhanced e-mail, location positioning, games (both online and offline), and Internet radio - from carrier networks to any BREW-enabled phone. BREW is competing for wireless software market share with J2ME (Java 2 Micro Edition), a similar platform from Sun Microsystems. The initial version of BREW is solely for CDMA networks; later versions could be enabled for time division multiple access (TDMA) and Global System for Mobile Communication (GSM) networks.
broadcast	Also see unicast, multicast, and anycast. In general, to broadcast (verb) is to cast or throw forth something in all directions at the same time. A radio or television broadcast (noun) is a program that is transmitted over airwaves for public reception by anyone with a receiver tuned to the right signal channel. The term is sometimes used in e-mail or other message distribution for a message sent to all members, rather than specific members, of a group such as a department or enterprise. On the Internet, certain Web sites deliver original or redistributed broadcasts from existing radio and television stations, using streaming sound or streaming video techniques, to Web users who visit the Web site or "tune it in" using a special program such as RealPlayer. Like publicly available radio and television broadcasts, Web broadcasts are available to anyone. The Web now offers live as well as prepackaged broadcasts and also plays back audio and video tapes. Some programming is scheduled and other prepackaged programs can be delivered on demand. Many Web users listen to music from a particular broacasting site as they surf other sites on the Web. Broadcast should not be confused with unicast, a transmission to a specific receiver (like most e-mail messages); multicast, a transmission to multiple specific receivers (as in e-mail to a distribution list or a Web transmission over the MBone network to a specific group of receiving addresses); or anycast, a transmission to the nearest of a group of routers, used in Internet Protocol Version 6 (IPv6) as a technique for chain-updating a group of routers with new routing information.
Browser	A Client program (software) that is used to look at various kinds of Internet resources.
BTW	By The Way A shorthand appended to a comment written in an online forum.
bug	A problem with computer software or hardware that causes it to malfunction or crash.
Byte	A set of Bits that represent a single character. The size of bytes varies from system to system. On the original home computers, bytes were composed of 8 bits. Now many computers operate with bytes that are 32 bits long.
C	The name of a sophisticated computer language commonly used for the creation of professional-grade applications. C is distinguished from other computer languages by its usage of pointers, variables that point at locations in memory. It was invented by Dennis Ritchie in the early 1970s.
C++	A computer language based on C that uses objected-oriented programming design principles.
CAPI	2 meanings: 1. (computer assisted personal interviewing) Surveying using a computer-based questionnaire. As an alternative to paper questionnaires, CAPI allows the interviewer to customize the survey, so that respondents answer questions only about subjects they're familiar with and receive questions in a random order to avoid biases. CAPI also seeks to improve accessibility to data and to make the interviewing process more entertaining. Although traditionally used on individual PCs, CAPI is now also being administered on the Web. 2. (common ISDN application programming interface) An application programming interface (API) standard used to access ISDN equipment (equipment that use the integrated services digital network [ISDN] standard for the transfer of data over telephone lines). When an application wants to communicate with an ISDN card it sends a standard series of commands to the card. These commands form the CAPI standard and give developers and users a chance to use a well-defined mechanism for communications over ISDN lines without being forced to adjust to hardware idiosyncrasies.
carrier	Short for carrier signal, carrier system, or carrier service provider: - carrier signal: A frequency in a communications channel modulated to carry analog or digital signal information. For example, an FM radio transmitter modulates the frequency of a carrier signal and the receiver processes the carrier signal to extract the analog information. An AM radio transmitter modulates the amplitude of a carrier signal. - carrier system: A communications system providing a number of point-to-point channels through some type of multiplexing. T-1 and T-3 carrier services are examples of carrier systems that can be used between points in a Wide Area Network (WAN). - carrier service provider: A company offering telephone and data communications between points in a state or in one or more countries. The Regional Bell Operating Companies (RBOCs) are example of carriers.
cascade	A series of reply posts to a USENET message, each adding a trivial or nonsense theme to the corpus of previous replies. Some consider this art; there is a USENET newsgroup devoted to propagating this self-expressive form (alt.cascade).
cc	Abbreviation for Carbon Copy. To cc: an e-mail message to someone is to send them a copy of the e-mail message.
CD	2 meanings: 1. Abbreviation for compact disk. 2. Abbreviation for change directory, a command in both the UNIX and DOS operating systems that assists in navigating a hierarchical directory structure.
CDMA	code-division multiple access Also see CDMA One, CDMA2000, and WCDMA. Compare time-division multiplex (TDM) and frequency-division multiplex (FDM). CDMA refers to any of several protocols used in so-called second-generation (2G) and third-generation (3G) wireless communications. As the term implies, CDMA is a form of multiplexing, which allows numerous signals to occupy a single transmission channel, optimizing the use of available bandwidth. The technology is used in ultra-high-frequency (UHF) cellular telephone systems in the 800-MHz and 1.9-GHz bands. CDMA employs analog-to-digital conversion (ADC) in combination with spread spectrum technology. Audio input is first digitized into binary elements. The frequency of the transmitted signal is then made to vary according to a defined pattern (code), so it can be intercepted only by a receiver whose frequency response is programmed with the same code, so it follows exactly along with the transmitter frequency. There are trillions of possible frequency-sequencing codes; this enhances privacy and makes cloning difficult. The CDMA channel is nominally 1.23 MHz wide. CDMA networks use a scheme called soft handoff, which minimizes signal breakup as a handset passes from one cell to another. The combination of digital and spread-spectrum modes supports several times as many signals per unit bandwidth as analog modes. CDMA is compatible with other cellular technologies; this allows for nationwide Roaming. The original CDMA standard, also known as CDMA One and still common in cellular telephones in the U.S., offers a transmission speed of only up to 14.4 Kbps in its single channel form and up to 115 Kbps in an eight-channel form. CDMA2000 and wideband CDMA deliver data many times faster.
CDMA One	CDMA One, also written cdmaOne, refers to the original ITU IS-95 (CDMA) wireless interface protocol that was first standardized in 1993. It is considered a second-generation (2G) mobile wireless technology. Today, there are two versions of IS-95, called IS-95A and IS-95B. The IS-95A protocol employs a 1.25-MHz carrier, operates in radio-frequency bands at either 800 MHz or 1.9 GHz, and supports data speeds of up to 14.4 Kbps. IS-95B can support data speeds of up to 115 kbps by bundling up to eight channels. Also see CDMA, WCDMA, and CDMA2000.
CDMA2000	CDMA2000, also known as IMT-CDMA Multi-Carrier or IS-136, is a code-division multiple access (CDMA) version of the IMT-2000 standard developed by the International Telecommunication Union (ITU). The CDMA2000 standard is third-generation (3-G) mobile wireless technology. CDMA2000 can support mobile data communications at speeds ranging from 144 Kbps to 2 Mbps. Deployment is in the planning stages. Versions have been developed by Ericsson and Qualcomm. Also see CDMA, WCDMA, and CDMA One.
cell	2 meanings: 1.In wireless telephony, a cell is the geographical area covered by a cellular telephone transmitter. The transmitter facility itself is called the cell site. The cell provided by a cell site can be from one mile to twenty miles in diameter, depending on terrain and transmission power. Several coordinated cell sites are called a cell system. When you sign up with a cellular telephone service provider, you generally are given access to their cell system, which is essentially local. When travelling out of the range of this cell system, the cell system can enable you to be transferred to a neighboring company's cell system without your being aware of it. This is called roaming service. The cell sites in a system connect to a Mobile Telephone Switching Office (MTSO), which in turn connects to the standard landline telephone system. 2. In a battery power source, a cell is a single energy or charge-storing unit within a pack of cells that form the battery. Each cell has a voltage rating that is combined with the other cells' voltages to form the overall battery voltage rating.
cell breathing	Cell breathing is the constant change of the range of the geographical area covered by a cellular telephone transmitter based on the amount of traffic currently using that transmitter. When a cell becomes heavily loaded, it shrinks. Subscriber traffic is then redirected to a neighboring cell that is more lightly loaded, which is called load balancing. Cell breathing is a common phenomenon of 2G and 3G wireless systems including code-division multiple access (CDMA). CDMA2000 and wideband code-division multiple access (WCDMA) are designed to manage cell breathing.
cellular telephone	Cellular telephone is a type of short-wave analog or digital transmission in which a subscriber has a wireless connection from a mobile telephone to a relatively nearby transmitter. The transmitter's span of coverage is called a cell. Generally, cellular telephone service is available in urban areas and along major highways. As the cellular telephone user moves from one cell or area of coverage to another, the telephone is effectively passed on to the local cell transmitter. A cellular telephone is not to be confused with a cordless telephone (which is simply a phone with a very short wireless connection to a local phone outlet). A newer service similar to cellular is personal communications services (PCS).
Certificate Authority	An issuer of Security Certificates used in SSL connections.
CGI	Common Gateway Interface A set of rules that describe how a Web Server communicates with another piece of software on the same machine, and how the other piece of software (the CGI program) talks to the web server. Any piece of software can be a CGI program if it handles input and output according to the CGI standard. CGI scripts can be written in many computer languages, but Perl and C are the most common.
cgi-bin	The most common name of a directory on a web server in which CGI programs are stored.
channel	3 meanings: 1. In communications, the term channel refers to a communications path between two computers or devices. It can refer to the physical medium (the wires) or to a set of properties that distinguishes one channel from another. For example, TV channels refer to particular frequencies at which radio waves are transmitted. IRC channels refer to specific discussions. 2. For IBM PS/2 computers, a channel is the same as an expansion bus. 3. In sales and marketing, the way in which a vendor communicates with and sells products to consumers.
channel bank	A channel bank is the foundation for all digital telecommunication transmissions. It is the part of a carrier -multiplex terminal that multiplexes a group of channels into a higher bit-rate digital channel and demultiplexes these aggregates back into individual channels. A channel bank changes analog voice and data signals into a digital format. It is called a "bank" because it can contain enough processing power to convert a bank of up to 24 individual channels to a digital format, and then back to analog again. The 24 channels comprise a T1 circuit. A channel bank can also multiplex a group of channels into a higher bandwidth analogue channel.
chat	A form of interactive online communication that enables typed conversations to occur in real-time. When participating in a chat discussion, your messages are instantaneously relayed to other members in the chat room while other members' messages are instantaneously relayed to you.
chat history	A transcript of a chat session.
chatter's block	A condition characterized by excessive anxiety about sending chat messages. The chatter with chatter's block feels that every message he types in a chat must be perfectly worded and perfectly timed. By striving to meet these standards of perfection, the chatter constantly erases and rewords his messages, often deciding not to send the messages at all. The cure for chatter's block is to relax. Everyone in a chat is expressing (and typing) ideas quickly and no one will blink an eye at the odd typo.
checksum	A mathematical calculation applied to the contents of a packet before and after it is sent. If the "before" calculation does not match the "after" calculation, there were errors in the transmission.
CHTML	Compact HTML CHTML (or cHTML) is a subset of standard Hypertext Markup Language (HTML) adapted for use with small computing devices such as personal digital assistants (PDAs), cellular phones, and smartphones. Access Company Ltd., a Japanese company, developed Compact HTML for use with i-Mode devices. Because handheld devices have display constraints, and limited power, storage, and memory resources, Compact HTML was created as a stripped-down version of the standard, excluding support for the more demanding features of HTML pages, such as image maps, backgrounds, varieties of fonts, frames , style sheets, and JPEG images. Compact HTML includes support for GIF images, and uses four buttons for operation, rather than two-dimensional cursor movement. Scrolling is not featured, because it is assumed that pages properly designed will fit the screen. Because Compact HTML is based on the universally used standard, it will enable small devices to connect to the open Web, rather than merely a section of it. It is expected that, in the future, several different levels of Compact HTML will be developed to adapt to the requirements of different applications. Also see Wireless Markup Language (WML), a similar markup language used with the Wireless Application Protocol (WAP).
churn	The turnover of users on an online service, especially after the expiration of a free trial period.
churning	Describes a computer taking a long time to process a particular operation. When a computer is churning, it may seem to be doing nothing.
circuit switching	A type of communications in which a dedicated channel (or circuit) is established for the duration of a transmission. The most ubiquitous circuit-switching network is the telephone system, which links together wire segments to create a single unbroken line for each telephone call. The other common communications method is packet switching, which divides messages into packets and sends each packet individually. The Internet is based on a packet-switching protocol, TCP/IP. Circuit-switching systems are ideal for communications that require data to be transmitted in real-time. Packet-switching networks are more efficient if some amount of delay is acceptable. Circuit-switching networks are sometimes called connection-oriented networks. Note, however, that although packet switching is essentially connectionless, a packet switching network can be made connection-oriented by using a higher-level protocol. TCP, for example, makes IP networks connection-oriented.
Client	2 meanings: 1.A software program that is used to contact and obtain data from a Server software program on another computer, often across a great distance. EachClient program is designed to work with one or more specific kinds of Server programs, and each Server requires a specific kind of Client. A Web Browser is a specific kind of Client. 2.Any computer system that requests a service of another computer system. A workstation requesting the contents of a file from a file server is a client of the file server.
client-server model	A configuration in which one computer, designated as a "server", sends information to a number of other "client" computers.
clipboard	A holding area that temporarily stores information copied or cut from a document. Both the Macintosh and Windows operating systems support this feature.
co-location	Most often used to refer to having a server that belongs to one person or group physically located on an Internet-connected network that belongs to another person or group. Usually this is done because the server owner wants their machine to be on a high-speed Internet connection and/or they do not want the security risks of having the server on thier own network.
coaxial line	Coaxial line, also called coaxial cable, consists of a wire conductor surrounded by a tubular, braided metallic shield. The conductor is kept at the center of the shield by a dielectric, which is usually solid or foamed polyethylene. The shield is connected to RF ground, while the center conductor carries the signal. The shield, as its name implies, prevents the electromagnetic field (EM field) inside the cable from escaping, and also prevents EM energy from entering the cable from outside. Coaxial cables are used at frequencies below approximately 1 gigahertz.
codec	3 meanings: 1. Short for compressor/decompressor, a codec is any technology for compressing and decompressing data. Codecs can be implemented in software, hardware, or a combination of both. Some popular codecs for computer video include MPEG, Indeo and Cinepak. 2. In telecommunications, (short for coder/decoder) a device that encodes or decodes a signal. For example, telephone companies use codecs to convert binary signals transmitted on their digital networks to analog signals converted on their analogue networks. 3. The translation of a binary value into a voltage that can be transmitted over a wire.
COFDM	coded orthogonal frequency division multiplexing COFDM is a modulation scheme that divides a single digital signal across 1,000 or more signal carriers simultaneously. The signals are sent at right angles to each other (hence, orthogonal) so they do not interfere with each other. COFDM is used predominately in Europe and is supported by the Digital Video Broadcasting (DVB) set of standards. In the U.S., the Advanced Television Standards Committee (ATSC) has chosen 8-VSB (8-level Vestigial Sideband) as its equivalent modulation standard. The main reason for Europe's decision to use COFDM is its ability to completely overcome multipath effects. When a signal is transmitted, it is met with obstructions such as canyons, buildings, and even people, which scatter the signal causing it to take two or more paths to reach its final destination, the television. The late arrival of the scattered portions of the signal cause ghost images. Multipath effects can occur simply by an individual walking into the room. For this very reason, some consumers in metropolitan areas or areas with rugged terrain opt for cable or satellite television instead of fighting their antennas for better reception. COFDM is resistant to multipath effects because it uses multiple carriers to transmit the same signal. Instead of the signal scattering when met with an obstacle, it flows around the obstacle like a river flows around a rock making it perfect for free DTV programming and for mobile television viewing. Problems with multipath effects were often cited in early evaluations of 8-VSB, although it is expected that devices such as internal antennas will overcome them. In Europe, stations transmit the same signal 100 percent of the time across many borders using single frequency networks. A single frequency network is a network of several stations that broadcast the same signal simultaneously using multiple transmitters. This allows television viewers to watch the same broadcast anywhere in Europe without interference. COFDM is ideal for single frequency networks.
collision detection	The process by which a node on a network monitors the communications line to determine when a collision (two nodes attempting to transmit at the same time) has occurred.
COM	2 meanings: 1. In DOS systems, the name of a serial communications port. DOS supports four serial ports: COM1, COM2, COM3, and COM4. However, most software uses system interrupts to access the serial ports, and there are only two IRQ lines reserved. This means that the four COM ports share the same two IRQ lines. Typically, COM1 and COM3 use IRQ4, while COM2 and COM4 use IRQ3. So in general, if you have two devices, one of which is attached to COM1 and the other to COM3, you cannot use them simultaneously. 2. Component Object Model
commercial online service	A computer network that supplies its members with access to chat rooms, bulletin boards, and other online content on a monthly fee basis. Commercial online services include America Online, CompuServe, The Microsoft Network, and Prodigy. In addition to their own proprietary content, most commercial online services also provide access to the Internet.
compile	To have a computer translate code written in a computer language into an executable form.
compression	A technology that reduces the size of a file. Compression programs like WinZip and UNIX compress are valuable to network users because they help save both time and bandwidth.
congestion	A state occurring in a part of a network when the message traffic is so heavy that it slows down network response time.
connection	When two computers have established a path through which the exchange of information can occur.
COO	Cell of Origin COO is a mobile positioning technique for finding a caller's cell (the basic geographical coverage unit of a cellular telephone system) location. It may be used by emergency services or commercial use. COO is the only positioning technique that is widely used in wireless networks and is used for Phase 1 of 911 service in the United States. For COO positioning, the location of the base station is ascertained and considered to be the location of the caller. COO is a variable and not a very precise locator; depending on the number of base stations in the search area, accuracy may be as close as within one hundred meters of the target (in an urban area) or as far off as thirty kilometers away from the target where base stations are less densely concentrated. For this reason, when precision is important COO is often used in conjunction with some other technology, such as the Global Positioning System (GPS) or Time of Arrival (TOA). Although COO positioning is not as precise as other methods, it offers unique advantages: it can very quickly identify the location (generally in about three seconds) and does not require equipment or network upgrades, which makes it easily deployed to existing customer bases. The American National Standards Institute (ANSI), and the European Telecommunications Standards Institute (ETSI) recently formed the T1P1 subcommittee dedicated to creating standardization for positioning systems using TOA, Assisted GPS, and Enhanced Observed Time Difference in addition to COO.
Cookie	The most common meaning of "Cookie" on the Internet refers to a piece of information sent by a Web Server to a Web Browser that the Browser software is expected to save and to send back to the Server whenever the browser makes additional requests from the Server.
coopetition	The phenomena of computer companies cooperating with their competitors on a project-by-project basis.
copy protection	A software lock placed on a computer program by its developer to thwart piracy. This preventative measure was widely used in the mid-1980s but later abandoned by many developers because of numerous customer complaints.
CPU	Central Processing Unit The main silicon chip that runs a computer's operating system and application software. It performs a computer's essential mathematical functions and controls essential operations. Intel CPUs in PCs were numbered by generation: 286, 386, 486. This numbering scheme was abandoned by Intel with the Pentium CPU, which would be the 586, and the Pentium Pro, which would the 686. Motorola PowerPC CPUs have maintained a consistent numbering convention: 601, 603, 604.
cracker	A malicious hacker who breaks (or cracks) the security of computer systems in order to access, steal, or destroy sensitive information. "Hacker" is often incorrectly used instead of cracker, especially by the media. See also hacker.
cross-posting	To post a single message simultaneously to multiple newsgroups or discussion groups. Gratuitous cross-posting is considered poor Netiquette.
crossload	To send an attached file via email. See also upload and download.
crunch	To efficiently process large amounts of information. A number cruncher, for example, is a routine or device optimized for and dedicated to processing numbers.
CU-SeeMe	Pronounced "See you, See me," CU-SeeMe is a publicly available videoconferencing program developed at Cornell University. It allows anyone with audio/video capabilities and an Internet connection to videoconference with anyone else with the same capabilities. It also allows multiple people to tie into the same videoconference.
cube	An original NeXT computer. The motherboard and drives for this machine are packed into a 12-inch matte black cube.
Cyberpunk	Cyberpunk was originally a cultural sub-genre of science fiction taking place in a not-so-distant, dystopian, over-industrialized society. The term grew out of the work of William Gibson and Bruce Sterling and has evolved into a cultural label encompassing many different kinds of human, machine, and punk attitudes. It includes clothing and lifestyle choices as well.
Cyberspace	Term originated by author William Gibson in his novel Neuromancer the word Cyberspace is currently used to describe the whole range of information resources available through computer networks.
daemon	In the UNIX operating system, a background process that lies dormant waiting to perform some useful task. The sendmail daemon, for example, continually runs but becomes active only when email is sent or received.
data encryption key	A string of characters used to mathematically encode a message so that it can only be read by someone in possession of another related key.
database	Loosely, any aggregation of data; usually a large collection of data that has been formatted by some user-defined standard.
DBS	direct broadcast satellite DBS refers to satellite television (TV) systems in which the subscribers, or end users, receive signals directly from geostationary satellites. Signals are broadcast in digital format at microwave frequencies. DBS is the descendant of direct-to-home (DTH) satellite services. A DBS subscriber installation consists of a dish antenna two to three feet (60 to 90 centimeters) in diameter, a conventional TV set, a signal converter placed next to the TV set, and a length of coaxial cable between the dish and the converter. The dish intercepts microwave signals directly from the satellite. The converter produces output that can be viewed on the TV receiver. A number of companies provide DBS and DTH service throughout the world. In the United States, DirecTV and EchoStar are the main vendors. Both of these corporations also provide satellite Internet service, which can be purchased for a monthly fee in addition to, or instead of, DBS TV service. In Canada, StarChoice and ExpressVu provide digital satellite TV for home users. Satellite-based TV and Internet services are popular in rural areas where conventional cable service is not available. DBS TV is also favored by urban and suburban subscribers who are not satisfied with the quality or quantity of TV programming available on conventional cable.
DCC	Direct Cable Connection A Windows 95 feature that enables two computers to be connected via a serial or parallel cable. Once connected, the two computers function as if they were on a local-area network (LAN). Either computer can access files on the other computer. But because DCC does not require network interface cards (NICs), it is less expensive and simpler. The limitations are that it can connect only two PCs, and the data transfer rate is slower than with a true LAN.
dedicated line	A telephone line that is reserved for the singular purpose of providing a data connection between two computers.
delivery receipt	An optional email feature that notifies you when your email message has been delivered to its recipient. See also Read Receipts.
delurk	To come out of online lurking mode; to actively participate in a online discussion after a period of just watching or lurking. This term is derived from episodes of Star Trek that feature Klingon warships that can hide ("cloak") or appear ("decloak") at will.
DES	Data Encryption Standard A popular, standard encryption scheme.
dial-up	2 meanings: 1. A temporary connection between computers established over a telephone line. 2. To establish a temporary connection to another computer.
DNS	Domain Name System A database system which looks up host IP addresses based upon domain names. For example if you ask for "www.thisismyhost.com" it will return "123.45.67.89". Copies of the Domain Name System are distributed through the Internet.
Domain Name	The unique name that identifies an Internet site. Domain Names always have 2 or more parts, separated by dots. The part on the left is the most specific, and the part on the right is the most general. A given machine may have more than one Domain Name but a given Domain Name points to only one machine. Domain names are derived from a hierarchical system, with a host name followed by a top-level domain category. The top-level domain categories are com (for commercial enterprises), org (for non-profit organizations), net (for network services providers), mil (for the military), and gov (for government). Some Internet domain names include the computer server name, other sub-domains, and/or country abbreviations (e.g., us). Domain names act as easy-to-remember addresses for product or company information. As such, they are often subject to disputes between competing commercial interests. Most domain names are assigned by the InterNIC.
domainism	Prejudice against people on the basis of their Internet address. For example, adopting a dismissive attitude towards anyone who posts from a commercial online service. "Why should anyone listen to you, you're posting from aol.com!"
DoPa	DoCoMo Packet Transmission DoPa is a packet-switched network service developed by NTT DoCoMo in Japan for Internet connection from mobile devices. NTT DoCoMo, Japan's leading wireless technology company, created their popular i-Mode service by adding features to DoPa that made it easier to use and allowed a wider range of content to be delivered. The transmission of packets allows the service to charge by the number of packets transmitted, so the customer pays for the volume of data, rather than according to call duration and distance, as is almost always tbe case with circuit-switched services.
DoS	Denial of Service
DOS	Disk Operating System. A dated operating system for PCs that features a command line interface.
downlink	These terms should not be confused with downstream and upstream. In satellite telecommunication, a downlink is the link from a satellite down to one or more ground stations or receivers, and an uplink is the link from a ground station up to a satellite. Some companies sell uplink and downlink services to television stations, corporations, and to other telecommunication carriers. A company can specialize in providing uplinks, downlinks, or both.
download	To transfer data from a larger "host" system to a smaller "client" system's hard drive or other local storage device. See also upload.
download charges	Monetary charges associated with downloading a file from a commercial online service. This method of information exchange is not very popular.
drag	To move an image or a window from one place on the screen to another by grabbing it and pulling it to a new location.
DS-CDMA	direct sequence code division multiple access DS-CDMA (also know as direct sequence spread spectrum) is one of two approaches to spread spectrum modulation for digital signal transmission over the airwaves. In direct sequence spread spectrum, the stream of information to be transmitted is divided into small pieces, each of which is allocated across to a frequency channel across the spectrum. A data signal at the point of transmission is combined with a higher data-rate bit sequence (also known as a chipping code) that divides the data according to a spreading ratio. The redundant chipping code helps the signal resist interference and also enables the original data to be recovered if data bits are damaged during transmission. Direct sequence contrasts with the other spread spectrum process, known as frequency hopping spread spectrum, or frequency hopping code division multiple access (FH-CDMA), in which a broad slice of the bandwidth spectrum is divided into many possible broadcast frequencies. In general, frequency-hopping devices use less power and are cheaper, but the performance of DS-CDMA systems is usually better and more reliable. Spread spectrum first was developed for use by the military because it uses wideband signals that are difficult to detect and that resist attempts at jamming. In recent years, researchers have turned their attention to applying spread spectrum processes for commercial purposes, especially in local area wireless networks.
DSL	Digital Subscriber Line A method for moving data over regular phone lines. A DSL circuit is much faster than a regular phone connection, and the wires coming into the subscriber's premises are the same (copper) wires used for regular phone service. A DSL circuit must be configured to connect two specific locations, similar to a leased line (however a DSL circuit is not a leased line). A common configuration of DSL allows downloads at speeds of up to 1.544 megabits (not megabytes) per second, and uploads at speeds of 128 kilobits per second. This arrangement is called ADSL: Asymmetric Digital Subscriber Line. Another common configuration is symmetrical: 384 Kilobits per second in both directions. In theory ADSL allows download speeds of up to 9 megabits per second and upload speeds of up to 640 kilobits per second. DSL is now a popular alternative to Leased Lines and ISDN, being faster than ISDN and less costly than traditional Leased Lines.
DSN	Deep Space Network The DSN is a sophisticated data communications system used by NASA (the U.S. National Aeronautics and Space Administration) in conjunction with manned and unmanned space missions. The DSN is also used by radio astronomers. The main terminal of the DSN is located at JPL (Jet Propulsion Laboratory) headquarters in Pasadena, California. There are three primary antennas, spaced equally on a great circle that slants around the world. All three are large paraboloid (dish) antennas that can be used for transmitting and receiving signals over a wide range of radio frequencies. One antenna is located in California, another is in Spain, and another is in Australia. The antennas are located in such a way that all existing operational spacecraft can be monitored and controlled, and communications maintained with them, almost 100 percent of the time. This is true of both earth-orbiting satellites and interplanetary space vehicles. Signals transmitted and received by DSN equipment include satellite control and telemetry, e-mail (including text, graphics, video, programs, and sound attachments), communications with the Space Shuttles, and radio-frequency emanations from distant celestial objects.
DSNG	digital satellite news gathering See SNG for more information.
DTE	Data Terminal Equipment A device that controls data flowing to or from a computer. The term is most often used in reference to serial communications defined by the RS-232C standard. This standard defines the two ends of the communications channel as being a DTE and Data Communications Equipment (DCE) device. In practical terms, the DCE is usually a modem and the DTE is the computer itself, or more precisely, the computer's UART chip. For internal modems, the DCE and DTE are part of the same device.
DTH	direct-to-home See DTH for more information
DTX	discountinuous transmission DTX is a method of momentarily powering-down, or muting, a mobile or portable wireless telephone set when there is no voice input to the set. This optimizes the overall efficiency of a wireless voice communications system. In a typical two-way conversation, each individual speaks slightly less than half of the time. If the transmitter signal is switched on only during periods of voice input, the duty cycle of the telephone set can be cut to less than 50 percent. This conserves battery power, eases the workload of the components in the transmitter amplifiers, and frees the channel so that time-division multiplexing (TDM) can take advantage of the available bandwidth by sharing the channel with other signals. A DTX circuit operates using voice activity detection (VAD). Sophisticated engineering is necessary to ensure that circuits of this type operate properly. In wireless transmitters, VAD is sometimes called voice-operated transmission (VOX).
dump	3 meanings: 1. A large mass of information that shows the exact contents of computer memory at a particular time. Dumps are used by programmers in the debugging process. 2. To send a large volume of information to somewhere specific such as a printer or a screen. 3. A backup or a backup file created by the UNIX dump utility.
E-mail	See Email.
E-ZPass	E-ZPass is a toll collection system in the northeastern U.S. that uses RFID technology to allow a driver to pass through a tollbooth and pay the toll without stopping the vehicle. Typically, the driver pre-pays a month of access tolls and is issued a transponder (a tag about the size of a deck of cards) that gets mounted on the inside of the windshield. When approaching a toll, the E-ZPass driver passes through a special booth that has an antenna. The antenna emits a radio frequency (RF) field that activates the driver's transponder, which in turn, sends back information about the driver's account to the antenna. The toll is then deducted from the driver's pre-paid account. E-Z Pass significantly cuts down on labor costs for toll collection and keeps the lines of traffic moving faster. Mobil Corporation uses a similar technology to enable drivers to purchase gasoline by using a transponder that attaches to the driver's key ring. Both E-ZPass and Mobil are experimenting with licensing their transponder payment systems to non-competitive vendors, such as McDonald's, who wish to move traffic through their fast food take-out windows more efficiently. In California, a system similar to E-ZPass is called FasTrak.
EAI	enterprise application integration EAI is the unrestricted sharing of data and business processes throughout the networked applications or data sources in an organization. Early software programs in areas such as inventory control, human resources, sales automation and database management were designed to run independently, with no interaction between the systems. They were custom built in the technology of the day for a specific need being addressed and were often proprietary systems. As enterprises grow and recognize the need for their information and applications to have the ability to be transferred across and shared between systems, companies are investing in EAI in order to streamline processes and keep all the elements of the enterprise interconnected. There are four major categories of EAI: - Database linking: databases share information and duplicate information as needed. - Application linking: the enterprise shares business processes and data between two or more applications. - Data warehousing: data is extracted from a variety of data sources and channeled into a specific database for analysis. - Common virtual system: the pinnacle of EAI; all aspects of enterprise computing are tied together so that they appear as a unified application.
EBPP	electronic bill presentment and payment The process by which companies bill customers and receive payments electronically over the Internet.
ecash	Electronic money designed to be used over a network or stored on cards similar to credit cards. Ecash is still more of an idea than a practical reality, largely due to security concerns.
EDGE	Enhanced Data GSM Environment A faster version of the Global System for Mobile (GSM) wireless service, is designed to deliver data at rates up to 384 Kbps and enable the delivery of multimedia and other broadband applications to mobile phone and computer users. The EDGE standard is built on the existing GSM standard, using the same time-division multiple access (TDMA) frame structure and existing cell arrangements. Ericsson notes that its base stations can be updated with software. EDGE is expected to be commercially available in 2001. It is regarded as an evolutionary standard on the way to Universal Mobile Telecommunications Service (UMTS).
eform	An electronic form that is filled out by a user and sent over a network. They are typically used to place orders or provide feedback. Eforms can be placed on web pages or in Java applets and usually contain text boxes, buttons, and other components.
Electronic Frontier Foundation	To quote their mission statement, "The Electronic Frontier Foundation is a non-profit civil liberties organization working in the public interest to protect privacy, free expression, and access to public resources and information online, as well as to promote responsibility in new media." Their WWW site is located at http://www.eff.org
ELF	extremely low frequency ELF refers to an electromagnetic field having a frequency much lower than the frequencies of signals typically used in communications. The most common ELF field is radiated by utility power lines. In the United States, this frequency is 60 Hz. You are exposed to these fields whenever you are near electrical appliances of any kind. In recent years, ELF fields have become a subject of concern in computing applications where cathode-ray tube (CRT) displays are used. These displays, typically used in desktop computer workstations and television sets, generate electromagnetic fields because of the strong, fluctuating currents in the electron-beam deflecting coils. The frequencies of these fields are on the order of a few kilohertz or less. Some studies suggest that ELF fields might have detrimental health effects on humans exposed to them for long periods of time. The claims vary from increased risk of cancer to premature births and miscarriages. However, as of this writing, conclusive proof has yet to be obtained that ELF fields are harmful at the levels encountered by computer users. The ELF fields surrounding a CRT display tend to be stronger off the sides of the CRT than directly in front of it or behind it. The fields diminish rapidly in intensity with increasing distance from the CRT. As a general rule, computer users should sit at least 18 inches away from a CRT display. Side-by-side workstations should be at least five feet apart. These considerations are important for visual comfort and "breathing room" as much as for minimizing the potential risk posed by ELF fields.
Email	Electronic Mail Messages, usually text, sent from one person to another via computer. E-mail can also be sent automatically to a large number of addresses.
Email Address	An electronic mail address. Email addresses follow the formula: user-ID@domain-name.
email overload	The state of being completely overwhelmed by the amount of email one has received.
EME	Earth-Moon-Earth EME (know as Moonbounce), is a form of wireless communication in which the moon is used as a passive satellite. To the uninitiated, this sounds a little like science fiction, but it has been done and continues to be done by experimentally-inclined amateur radio operators. There are several challenges and difficulties inherent in moonbounce operation. One of the most troublesome for two-way communication is the fact that the moon's distance introduces lag time. The moon is approximately 250,000 miles away from the earth, and radio waves travel at 186,282 miles per second. A signal sent to the moon does not return until 2.7 seconds have elapsed. If two people are engaged in a conversation and one person asks a question, that person cannot expect a reply until at least 5.4 seconds later (the answer must travel to the moon and back, as must the question). Besides propagation delay, the path loss to and from the moon is considerable. The moon is a relatively poor reflector of electromagnetic rays at any wavelength, including radio waves. Its surface is irregular, and it scatters, rather than focusing, reflected energy. Because of this, sophisticated equipment is necessary to successfully bounce a signal off the moon and hear it return. Another problem with moonbounce communication is libration fading and Doppler shifting. The moon does not always present exactly the same face; it "wobbles" a few degrees back and forth. This "wobbling," called libration, produces a constant change in every component of any signal reflected from the moon. The returned signal consists of the sum total of countless rays that have bounced off mountains, boulders, crater walls, and other lunar features. The relative phase of these components rapidly fluctuates because of libration, so any signal returning from the moon is "fluttery" and distorted.
EMS	Enhanced Messaging Service EMS is an adaptation of the Short Message Service (SMS) that allows users to send and receive ring tones and operator logos, as well as combinations of simple media to and from EMS-compliant handsets. Because EMS is based on SMS, it can use SMS Centers (SMSCs) the same way that SMS does. EMS works on all Global System for Mobile communications (GSM) networks (widely used in Europe and increasingly available elsewhere). If a message is sent to a phone that is not EMS-capable, the recipient will still receive the text portion of the message. EMS users can integrate text, melodies, pictures, sounds, and animations to enhance the expressive power of messages that are limited by the display constraints of mobile devices. Message senders can use images, sounds, and animation they download from an online library or create images and sounds directly on the phone. EMS is an open standard developed by the Third Generation Partnership Project (3GPP), a mobile telecommunications standards collaborative. The standard is being actively promoted by Alcatel, Ericsson, Motorola, and Siemens. Nokia is promoting a similar standard, Multimedia Messaging Service (MMS).
emulation	Refers to the ability of a program or device to imitate another program or device. Many printers, for example, are designed to emulate Hewlett-Packard LaserJet printers because so much software is written for HP printers. By emulating an HP printer, a printer can work with any software written for a real HP printer. Emulation tricks the software into believing that a device is really some other device. Communications software packages often include terminal emulation drivers . This enables your PC to emulate a particular type of terminal so that you can log on to a mainframe. It is also possible for a computer to emulate another type of computer. For example, there are programs that enable an Apple Macintosh to emulate a PC.
encryption	A procedure that renders the contents of a message or file unintelligible to anyone not authorized to read it. PGP (Pretty Good Privacy) is a commonly-used encryption program.
EPOC	EPOC is an operating system designed for small, portable computer-telephones with wireless access to phone and other information services. EPOC is based on an earlier operating system from Psion, the first major manufacturer of personal digital assistants (PDAs). The name derived from the company's belief that the world is entering "a new epoch of personal convenience." To earlier systems, EPOC adds wireless communication and an architecture for adding application programs. Psion declared its first version of EPOC to be an open operating system and licensed it to other equipment makers. Psion then formed a new company with Ericsson, Nokia, and later Motorola called Symbian, which now licenses EPOC and continues to develop it. For portable equipment manufacturers, EPOC is an alternative to Microsoft's Windows CE. (The popular Palm PDA uses its own proprietary operating system, PalmOS.). Symbian refers to the class of hardware EPOC serves as "wireless information devices." EPOC is a 32-bit, multitasking operating system that supports a pen-based graphical user interface (GUI). It is written in the C++ programming language using an object-oriented programming design. The code is very compact so that it can fit on a small ROM chip. In addition to basic services, the operating system comes with an "application suite," that includes a word processor, e-mail handler, spreadsheet program, a scheduling application, general purpose database, sketch program, world clock, voice recorder, spell checker, calculator, communication programs, and a Web browser. EPOC can be scaled from relatively large configurations for a fully-functional handheld computer to small configurations for embedded systems programming applications. Although EPOC can be ported to other microprocessors, Symbian's preferred platform is the Advanced RISC Machines (ARM) architecture. Symbian considers ARM the best platform in terms of millions of instructions per second (MIPS) per watt and per dollar cost. Symbian provides development kits for C++, for OPL (a BASIC-like language), and for Java. Programmers write programs at a PC and use an emulator to test them.
ESMR	Enhanced Specialized Mobile Radio ESMR is a wireless communication system in which numerous mobile/portable transceivers are linked in a network of repeaters. Each repeater has a range of approximately 5 to 10 miles. Operating frequencies are in the UHF (ultra-high-frequency) range, that is, between approximately 300 MHz and 3 GHz. Usually, the working band is near 900 MHz. ESMR can function like its fundamentally simpler cousin, SMR, but it can also offer features similar to those of a cellular telephone network. The PTT (push-to-talk), half-duplex mode can be used; in this case the operation resembles communications between old style two-way radios. full-duplex mode can also be used, so either party can listen and talk at the same time. Interconnection with the telephone networks is commonly done. In addition to voice communication, an ESMR system can offer paging, wireless fax, and data transmission. ESMR systems use digital radio transmission. Spread-spectrum modes, such as frequency hopping, are common. In a well-designed ESMR system, connection is almost instantaneous, compared with the typical 15 to 20 seconds required to dial and set up a call in a public cellular network. The coverage of an ESMR system depends on the geographical distribution and needs of the users. Some systems are confined to single municipalities; others cover selected groups of metro areas; others operate over entire states or regions of a country. Examples of ESMR networks include Ericsson's EDACS (Enhanced Digital Access Communications System), Motorola's IDEN (Integrated Dispatch Enhanced Network), and the Nextel System.
Ethernet	A standard method of connecting computers to a local area network using coaxial cable invented by Robert Metcalfe at Xerox PARC in the early 1970s. There is more than one type of Ethernet. By 2001 the standard type was "100-BaseT" which can handle up to about 100,000,000 bits-per-second and can be used with almost any kind of computer.
Evernet	The term Evernet has been used to describe the convergence of wireless, broadband, and Internet telephony technologies that will result in the ability to be continuously connected to the Web anywhere using virtually any information device. Considered the next generation of Internet access, the Evernet assumes the emergence of an amount of bandwidth that would enable millions of homes to access the Web through inexpensive cable modem, DSL, or wireless connections. The "Evernet" can also be considered to include common household appliances and home and office networks that include devices that control the environment; such networks require an "always on" capability. In addition, portable devices that can connect quickly and easily without wires to other devices (see Bluetooth) might also be considered part of the Evernet.
execute	To process or run a computer program.
Extranet	An intranet that is accesible to computers that are not hysically part of a companys' own private network, but that is not accessible to the general public, for example to allow vendors and business partners to access a company web site. Often an intranet will make use of a Virtual Private Network (VPN.)
facilitated chat	In a facilitated chat, a host or facilitator controls the messages that appear on the chat screen. Usually used when there is a guest speaker. Facilitated chats provide an orderly environment for the guest speaker and ensure that she is not overwhelmed with dozens of questions all being asked at once. See also chat.
FAQ	Frequently Asked Questions FAQs are documents that list and answerthe most common questions on a particular subject. There are hundreds of FAQs on subjects as diverse as Pet Grooming and Cryptography. FAQs are usually written by people who have tired of answering the same question over and over.
FDDI	Fiber Distributed Data Interface A standard for transmitting data on optical fiber cables at a rate of around 100,000,000 bits-per-second (10 times as fast as 10-BaseT Ethernet, about twice as fast as T-3).
feed line	In a wireless communications or broadcasting antenna system, the feed line connects the antenna to the receiver, transmitter, or transceiver. The line transfers radio-frequency (RF) energy from a transmitter to an antenna, and/or from an antenna to a receiver, but, if operating properly, does not radiate or intercept energy itself. There are three types of antenna feed lines, also called RF transmission lines, commonly used in wireless systems.
FH-CDMA	frequency hopping code division multiple access Frequency hopping is one of two basic modulation techniques used in spread spectrum signal transmission. It is the repeated switching of frequencies during radio transmission, often to minimize the effectiveness of "electronic warfare" - that is, the unauthorized interception or jamming of telecommunications. It also is known as frequency- hopping code division multiple access (FH-CDMA). Spread spectrum modulation techniques have become more common in recent years. Spread spectrum enables a signal to be transmitted across a frequency band that is much wider than the minimum bandwidth required by the information signal. The transmitter "spreads" the energy, originally concentrated in narrowband, across a number of frequency band channels on a wider electromagnetic spectrum. Benefits include improved privacy, decreased narrowband interference, and increased signal capacity. In an FH-CDMA system, a transmitter "hops" between available frequencies according to a specified algorithm, which can be either random or preplanned. The transmitter operates in synchronization with a receiver, which remains tuned to the same center frequency as the transmitter. A short burst of data is transmitted on a narrowband. Then, the transmitter tunes to another frequency and transmits again. The receiver thus is capable of hopping its frequency over a given bandwidth several times a second, transmitting on one frequency for a certain period of time, then hopping to another frequency and transmitting again. Frequency hopping requires a much wider bandwidth than is needed to transmit the same information using only one carrier frequency. The spread spectrum approach that is an alternative to FH-CDMA is direct sequence code division multiple access (DS-CDMA), which chops the data into small pieces and spreads them across the frequency domain. FH-CDMA devices use less power and are generally cheaper, but the performance of DS-CDMA systems is usually better and more reliable. The biggest advantage of frequency hopping lies in the coexistence of several access points in the same area, something not possible with direct sequence. Certain rules govern how frequency-hopping devices are used. In North America, the Industrial, Scientific, and Medial (ISM) waveband is divided into 75 hopping channels, with power transmission not to exceed 1 watt on each channel. These restrictions ensure that a single device does not consume too much bandwidth or linger too long on a single frequency. The Federal Communications Commission (Fcc) has amended rules to allow frequency hopping spread spectrum systems in the unregulated 2.4 GHz band. The rule change is designed to allow wider bandwidths, thus enabling Internet devices to operate at higher speeds and fostering development of wireless LANs and wireless cable modems.
FidoNet	A worldwide hobbyist network of personal computers started in 1984 that exchanges mail, discussion groups, and files.
file compression	Reducing the size of files for ease of storage and transfer. WinZip is an example of an application that compresses files; the UNIX compress utility is another.
file transfer	The process of moving or transmitting a file from one location to another, as between two programs or from one computer to another.
Finger	A UNIX utility that reports information about other users who have UNIX accounts. Finger can tell you, for example, where and when a person last logged in to the system. It can also be used on a single host or across the Internet. Finger is also sometimes used to give access to non-personal information, but the most common use is to see if a person has an account at a particular Internet site. Many sites do not allow incoming Finger requests, but many do.
Firewall	A combination of hardware and software that separates a Network into two or more parts for security purposes. A set of security procedures that separates and protects data on a LAN from crackers who might access the LAN from the Internet.
fixed wireless	Fixed wireless refers to the operation of wireless devices or systems in fixed locations such as homes and offices. Fixed wireless devices usually derive their electrical power from the utility mains, unlike mobile wireless or portable wireless which tend to be battery-powered. Although mobile and portable systems can be used in fixed locations, efficiency and bandwidth are compromised compared with fixed systems. Mobile or portable, battery-powered wireless systems can serve as emergency backups for fixed systems in case of a power blackout or natural disaster. The technology for wireless connection to the Internet is as old as the Net iteself. Amateur radio operators began "patching" into telephone lines with fixed, mobile, and portable two-way voice radios in the middle of the 20th Century. A wireless modem works something like an amateur-radio "phone patch," except faster. High-end fixed wireless employs broadband modems that bypass the telephone system and offer Internet access hundreds of times faster than twisted-pair hard-wired connections or cell-phone modems.
flash session	A feature of America Online that automatically performs online tasks at a designated time. Flash sessions are often used to send/receive email and download large files.
flat-file	2 meanings: 1. As a noun, an ASCII text file consisting of records of a single type, in which there is no embedded structure information governing relationships between records. 2. As an adjective, describes a flattened representation of a database as single file from which the structure could implicitly be rebuilt.
flow control	2 meanings: 1. In communications, the process of adjusting the flow of data from one device to another to ensure that the receiving device can handle all of the incoming data. This is particularly important where the sending device is capable of sending data much faster than the receiving device can receive it. There are many flow control mechanisms. One of the most common flow control protocols for asynchronous communication is called xon-xoff. In this case, the receiving device sends a an xoff message to the sending device when its buffer is full. The sending device then stops sending data. When the receiving device is ready to receive more data, it sends an xon signal. Flow control can be implemented in hardware or software, or a combination of both. 2.In programming, the statements and other constructs that control the order in which operations are executed. For example, common looping statements such as for…next and while are known as flow control statements. Branching statements, such as if…then are also part of a programming language's flow control mechanism.
font	A typographic style used to display or print characters. Times Roman, Courier, and Helvetica are three examples.
foreign agent	In Mobile Internet Protocol (Mobile IP), a foreign agent is a router serving as a mobility agent for a mobile node. As specified in IETF RFC 2002), a foreign agent works in conjunction with another type of mobility agent known as a home agent to support Internet traffic forwarding for a device connecting to the Internet from any location other than its home network. The home agent tunnels datagrams (packets) intended for the mobile node to a care-of address, which is either the IP address for the foreign agent, or an IP address acquired through some external means, such as Dynamic Host Configuration Protocol (DHCP). The foreign agent detunnels packets and delivers them to the mobile node. The operational mode using the foreign agent's static IP address as the care-of address was favored in the Internet Protocol version 4 (IPv4) environment (which has a limited number of IP addresses available), because it meant that many devices could use the same care-of address. However, because Internet Protocol version 6 (IPv6) virtually does away with address constraints, Mobile IPv6 (MIPv6) minimizes the use of foreign agents.
foreign network	In the Mobile Internet Protocol (Mobile IP), a foreign network is any network other than the home network to which a mobile device may be connected. Because standard Internet routing mechanisms deliver all traffic to a device's home network, it was once necessary to change a mobile device's IP address each time it connected through a foreign network. To overcome this drawback, the Internet Engineering Task Force (IETF) has developed the Mobile IP standard and several enhancements to it.
forum	A topically-focused discussion group or area. From the traditional Roman forum -- a community area where ideas and proposals are discussed.
forwarding	Sending an email message or post from one person to a third party.
frame	4 meanings: 1. An HTML feature that allows web designers to segment the window of a web browser into distinct sections. 2. A single complete picture in a moving picture sequence. 3. In graphics and desktop publishing applications, a rectangular area in which text or graphics can appear. 4. In communications, a packet of transmitted information.
freenet	A community-based bulletin board system that serves a local geographic community on a non-profit basis.
freeware	Shareware that is openly available to the public without the requirement of user registration fee.
fried	To be totally destroyed or otherwise unusable, as in "my hard drive is fried" or "the network is totally fried."
FSO	free space optics Free space optics technology, also referred to as "open-air photonics" or "optical wireless" or "infrared broadband," transmits data from point to point and multipoint using low-powered infrared lasers. Unlike traditional copper wires or fiber-optic technology, which transmits data by light across glass, FSO uses laser technology to send optical signals through the air using lenses and mirrors to focus and redirect the beams and send data from one chip to another. And unlike radio frequencies, FSO technology does not require a spectrum license. An FSO system uses optical amplifiers and a telescope that sends multiple wavelengths of light in direct line of sight through the atmosphere to another telescope waiting to receive the information. The receiving telescope is connected to a highly sensitive receiver through an optical fiber and a DWDM demultiplexer. Since the system is bidirectional, each telescope can simultaneously send and receive information. The only weather condition that affects an FSO transmission is fog. Fog can corrupt the direct line of sight between the two telescopes because the moisture particles in the air are so small and dense that they act as millions of tiny prisms dissipating the band of light sent from the laser. Free space optics provides a higher bandwidth to the end user at a faster speed. The photons transmitted by the laser are much quicker than electrons moving along a wire and they can pass straight through each other, which charge-bearing electrons cannot do. Because of this, large amounts of data, such as IP -based voice and video, can be transmitted through a narrow corridor of space.
FSP	free-space photonics See FSO (free-space optics)
FTP	File Transfer Protocol A protocol that enables you to transfer files between computers on the Internet. A very common method of moving files between two Internet sites. FTP is a way to login to another Internet site for the purposes of retrieving and/or sending files. There are many Internet sites that have established publicly accessible repositories of material that can be obtained using FTP, by logging in using the account name "anonymous", thus these sites are called "anonymous ftp servers". FTP was invented and in wide use long before the advent of the World Wide Web and originally was always used from a text-only interface.
FUD	Fear, Uncertainty, and Doubt. A set of sales tactics employed by market leaders to cast aspersion on competing products. Computer products are often purchased on the basis of perceived market leadership because no one wants to get stuck with a losing product that might not be supported in the near future. The usefulness of using FUD to confuse a market is epitomized by the apocryphal saying, "No one ever got fired for buying IBM." A good example of FUD is Microsoft's tactic of pre-announcing products far in advance of their actual availability. All of a sudden the market for competing products evaporates as customers await a dominating Microsoft product.
full duplex	Refers to the transmission of data in two directions simultaneously. For example, a telephone is a full-duplex device because both parties can talk at once. In contrast, a walkie-talkie is a half-duplex device because only one party can transmit at a time. Most modems have a switch that lets you choose between full-duplex and half-duplex modes. The choice depends on which communications program you are running. In full-duplex mode, data you transmit does not appear on your screen until it has been received and sent back by the other party. This enables you to validate that the data has been accurately transmitted. If your display screen shows two of each character, it probably means that your modem is set to half-duplex mode when it should be in full-duplex mode.
garbage	2 meanings: 1. A string of unwanted, meaningless, or unintelligible characters produced by error. 2. Incorrect input to a computer. See GIGO.
Gateway	The technical meaning is a hardware or software set-up that translates between two dissimilar protocols, for example America Online has a gateway that translates between its internal, proprietary e-mail format and Internet e-mail format. Another, sloppier meaning of gateway is to describe any mechanism for providing access to another system, e.g. AOL might be called a gateway to the Internet.
GIF	Graphic Interchange Format A common format for image files, especially suitable for images containing large areas of the same color. GIF format files of simple images are often smaller than the same file would be if stored in JPEG format, but GIF format does not store photographic images as well as JPEG.
Gigabyte	1000 or 1024 Megabytes, depending on who is measuring.
GIGO	Garbage In Garbage Out. Usually said in response to complaints that a program didn't "do the right thing" when given bad or flawed input. See garbage.
GLONASS	Globalnaya Navigatsionnay Sputnikovaya Sistema GLONASS, the Russian Federation's Global Navigation Satellite System (GNSS), is the Russian version of a global positioning system. Similar to the United States' Global Positioning System (GPS), GLONASS is owned and operated by the military. GLONASS provides two separate levels of precision: deliberately degraded (for security purposes) signals for civilian users offer accuracy to within 100 meters, while its signals for military users offer accuracy of 10-20 meters. GLONASS was designed to operate a system of 24 satellites (21 operational, and three spares for failover redundancy) orbiting at a height of 19,140 kilometers in three circular planes, at an inclination of 64.8 degrees relevant to the equatorial plane. However, because of a lack of maintenance funding, fewer than half of the GLONASS satellites are likely to be in operation at any given time.
GNSS	Galileo is the informal name for the European Global Navigation Satellite System (GNSS), a system that will offer users anywhere in the world "near pinpoint" geographic positioning when it becomes fully operational by 2008. Designed to be interoperable with the other two such systems, the United States' Global Positioning System (GPS) and Russia's Global Orbiting Navigation Satellite System (GLONASS), Galileo will enable a user to take a position from any combination of satellites with a single receiver. Both GLONASS and GPS are run by the defense departments of their respective countries. Galileo will be civilian-operated. The Galileo system, which consists of 30 satellites orbiting the earth at a height of 15,000 miles, is expected to pinpoint a geographical position to within a single meter. Because the service's availability will be guaranteed in almost any circumstance, the system will be ideal for applications in which precision and reliability are critical, such as air traffic management (among many possible examples). Galileo will also perform global search and rescue (SAR) functions, based on the Cospas-Sarsat SAR system. Each satellite will have its own transponder, which will transfer distress signals from a user's transmitter to a rescue co-ordination center. Once the rescue operation is launched, the system will transmit a signal to the user, to notify them that help is on the way. When fully deployed, the Galileo system will use 27 operational satellites and three spares for failover redundancy. The satellites will be positioned in three circular Medium Earth Orbit (MEO) planes 15,000 miles up, at an inclination of 56 degrees relative to the equatorial plane. Two Galileo Control Centers (GCC) will be located in Europe; these centers will receive data from a global network of twenty Galileo Sensor Stations (GSS). GSS data will allow the control centers to synchronize the time signals of satellites with the ground station clocks, and to calculate data about system integrity. Five S-Band (2.0-4.0 GHz) and 10 C-Band (4.0-8.0 GHz) uplink stations around the globe will manage the flow of data between the satellites and the control centers. Galileo is named for the Italian astronomer, mathematician, and physicist, Galileo Galilei. In the 16th and 17th centuries, Galileo applied mathematics to the study of physical science. This new approach, coupled with discoveries through the telescope, revolutionized both astronomy and the study of motion. Galileo is also the name of an unmanned American spacecraft sent to explore Jupiter and its moons in the mid-to-late 1990s.
Gopher	Invented at the University of Minnesota in 1993 just before the Web, gopher was a widely successful method of making menus of material available over the Internet. Gopher was designed to be much easier to use than FTP, while still using a text-only interface. Gopher is a Client and Server style program, whichrequires that the user have a Gopher Client program. Although Gopher spread rapidly across the globe in only a couple of years, it has been largely supplanted by Hypertext, also known as WWW (World Wide Web). There are still thousands of Gopher Servers on the Internet and we can expect they will remain for a while.
GPRS	General Packet Radio Services GPRS is a packet-based wireless communication service that promises data rates from 56 up to 114 Kbps and continuous connection to the Internet for mobile phone and computer users. The higher data rates will allow users to take part in video conferences and interact with multimedia Web sites and similar applications using mobile handheld devices as well as notebook computers. GPRS is based on Global System for Mobile (GSM) communication and will complement existing services such circuit-switched cellular phone connections and the Short Message Service (SMS). In theory, GPRS packet-based service should cost users less than circuit-switched services since communication channels are being used on a shared-use, as-packets-are-needed basis rather than dedicated only to one user at a time. It should also be easier to make applications available to mobile users because the faster data rate means that middleware currently needed to adapt applications to the slower speed of wireless systems will no longer be needed. As GPRS becomes available, mobile users of a virtual private network (VPN) will be able to access the private network continuously rather than through a dial-up connection. GPRS will also complement Bluetooth, a standard for replacing wired connections between devices with wireless radio connections. In addition to the Internet Protocol (IP), GPRS supports X.25, a packet-based protocol that is used mainly in Europe. GPRS is an evolutionary step toward Enhanced Data GSM Environment (EDGE) and Universal Mobile Telephone Service (UMTS).
GPS	Global Positioning System The GPS is a "constellation" of 24 well-spaced satellites that orbit the Earth and make it possible for people with ground receivers to pinpoint their geographic location. The location accuracy is anywhere from 100 to 10 meters for most equipment. Accuracy can be pinpointed to within one (1) meter with special military-approved equipment. GPS equipment is widely used in science and has now become sufficiently low-cost so that almost anyone can own a GPS receiver. The GPS is owned and operated by the U.S. Department of Defense but is available for general use around the world. Briefly, here's how it works: - 21 GPS satellites and three spare satellites are in orbit at 10,600 miles above the Earth. The satellites are spaced so that from any point on Earth, four satellites will be above the horizon. - Each satellite contains a computer, an atomic clock, and a radio. With an understanding of its own orbit and the clock, it continually broadcasts its changing position and time. (Once a day, each satellite checks its own sense of time and position with a ground station and makes any minor correction.) - On the ground, any GPS receiver contains a computer that "triangulates" its own position by getting bearings from three of the four satellites. The result is provided in the form of a geographic position - longitude and latitude - to, for most receivers, within 100 meters. - If the receiver is also equipped with a display screen that shows a map, the position can be shown on the map. - If a fourth satellite can be received, the receiver/computer can figure out the altitude as well as the geographic position. - If you are moving, your receiver may also be able to calculate your speed and direction of travel and give you estimated times of arrival to specified destinations. The GPS is being used in science to provide data that has never been available before in the quantity and degree of accuracy that the GPS makes possible. Scientists are using the GPS to measure the movement of the arctic ice sheets, the Earth's tectonic plates, and volcanic activity. GPS receivers are becoming consumer products. In addition to their outdoor use (hiking, cross-country skiing, ballooning, flying, and sailing), receivers can be used in cars to relate the driver's location with traffic and weather information.
grep	2 meanings: 1. To rapidly scan a large volume of information looking for a particular string or pattern. 2. A UNIX command used to scan a file or group of files for a matching search string or pattern.
GUI	Graphical User Interface. A set of screen presentations and metaphors that utilize graphic elements such as icons in an attempt to make an operating system easier to use. Unlike UNIX and DOS, which feature a command line interface, the Windows and the Macintosh operating systems present graphical environments for input and output.
guru	An expert who acts as a knowledge resource for others and who is generally venerated by the people whose problems he or she solves.
hacker	An expert programmer who likes to spend a lot of t