computer glossary of terms.

Active Channels An Active Channel is what Microsoft calls a Web site that has been enabled for push delivery to Internet Explorer 4.0 browsers. To create a channel, developers write and upload a CDF (channel definition format) file to their Web site; new content is delivered to users automatically when the site is updated. Developers and subscribers can control the update frequency; which channels, subchannels, and items (sections) are subscribed to; and other channel characteristics. Most Active Channels use dynamic HTML (DHTML) and other effects to spice up content and make it more interactive.

ADSL Asymmetric Digital Subscriber Line Like ISDN, ADSL uses standard phone lines to deliver high-speed data communications. But while ISDN's transmission speed is limited to 64 kbps, ADSL technology can deliver upstream (from the user) speeds of 640 kbps and downstream (to the user) speeds of more than 6 mbps. Even better, ADSL uses the portion of a phone line's bandwidth not utilized by voice, allowing for simultaneous voice and data transmission.

Analog The traditional method of modulating radio signals so that they can carry information. Amplitude modulation (AM) and frequency modulation (FM) are the two most common methods of analog modulation. Today, most U.S. cellular systems carry phone conversations using analog; the transition to digital transmissions is happening slowly

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.

AT commands AT is a contraction of attention, a command used to program SmartModems from Hayes Microcomputer Products. AT commands program a variety of modem hardware settings and were adopted by other modem manufacturers who wanted to market their wares with the coveted phrase Hayes-compatible. At one time, you couldn't call yourself an online aficionado if you didn't know that ATL0 turned your modem speaker way down and ATM0 turned it off. Now the commands are usually hidden under a menu option in your communication software.

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.

bandwidth
In a general sense, this term describes information-carrying capacity. It can apply to telephone or network wiring as well as system buses, radio frequency signals, and monitors. On a more human level, the term can describe a person's capacity for dealing with multiple projects ("I'd like to update this database, but I don't have the bandwidth."). Bandwidth is most accurately measured in cycles per second, or hertz (Hz), which is the difference between the lowest and highest frequencies transmitted. But it's also common to use bits or bytes per second instead. Usually measured in bits-per-second. A full page of English text is about 16,000 bits. A fast modem can move about 57,000 bits in one second. Full-motion full-screen video would require roughly 10,000,000 bits-per-second, depending on compression.

Baud In common usage the baud rate of a modem is how many bits it can send or receive per second. Technically, baud is the number of times per second that the carrier signal shifts value - for example a 1200 bit-per-second modem actually runs at 300 baud, but it moves 4 bits per baud (4 x 300= 1200 bits per second).

Binary
Information consisting entirely of ones and zeros. Also, commonly used to refer to files that are not simply text files, e.g. images.

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 what's coded into a PC's ROM to provide the basic instructions for controlling system hardware. The operating system and application programs both directly access BIOS routines to provide better compatibility for such functions as screen display. Some makers of add-in boards such as graphics accelerator cards provide their own BIOS modules that work in conjunction with (or replace) the BIOS on the system's motherboard.

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. Bandwidthis usually measured in bits-per-second.

Blog From "Web log." A blog is basically a journal that is available on the web. The activity of updating a blog is "blogging" and someone who keeps a blog is a "blogger."

Boolean English mathematician George Boole (1815-64) founded a field of mathematical and philosophical study called symbolic logic. His name is now used most often to describe a subset of symbolic logic: constructing database queries.

Whenever you see a Web search tool or database query system that allows you to use AND, OR, and NOT to hone your search, the chances are it uses Boolean techniques. The most common Boolean operators are AND (you're looking for all terms), OR (you're looking for at least one of the terms), and NOT (you're excluding a term). You'll always see the operators referred to in uppercase letters, although you usually don't need to enter them that way to make a Boolean search work properly. Also, the Boolean operator AND doesn't work like a normal English and. For example, a Boolean search through a database of rock musicians for members of the Beatles AND Wings would turn up only Paul McCartney.

bps -- (Bits-Per-Second) A measurement of how fast data is moved from one place to another. A 56K modem can move about 57,000 bits per second.

bus In broadest terms, a bus is a common connection between electrical devices. In computerese, bus most commonly means the data pathway that connects a processor to memory and to other "peripheral" buses, such as VESA and PCI.

Byte A set of Bits that represent a single character. Usually there are 8 Bits in a Byte, sometimes more, depending on how the measurement is being made.

cache Caches come in many types, but they all work the same way: they store information where you can get to it fast. A Web browser cache stores the pages, graphics, sounds, and URLs of online places you visit on your hard drive; that way, when you go back to the page, everything doesn't have to be downloaded all over again. Since disk access is much faster than Internet access, this speeds things up. Of course, disk access is slower than RAM access, so there's also disk caching, which stores information you might need from your hard disk in faster RAM.

Cardbus Cardbus is a specification that allows PCMCIA cards to transfer data at rates exceeding 100MB/sec. Older, 16-bit PCMCIA cards transfer data at a rate of 20MB/sec.

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 (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-bin The most common name of a directory on a web server in which CGI programs are stored.

Client A software program that is used to contact and obtain data from a Server software program on another computer, often across a great distance. Each Client 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.

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.

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. Depending on the type of Cookie used, and the Browsers' settings, the Browser may accept or not accept the Cookie, and may save the Cookie for either a short time or a long time. Cookies might contain information such as login or registration information, online "shopping cart" information, user preferences, etc. When a Server receives a request from a Browser that includes a Cookie, the Server is able to use the information stored in the Cookie. For example, the Server might customize what is sent back to the user, or keep a log of particular users' requests. Cookies are usually set to expire after a predetermined amount of time and are usually saved in memory until the Browser software is closed down, at which time they may be saved to disk if their "expire time" has not been reached.

COM port Although it's in all capital letters, COM is not an acronym. It's a contraction of communications, and it's used to describe the serial port on a PC. COM is generally used in conjunction with a number, as in COM1, COM2, COM3, or COM4.

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. For example, the domain names: can all refer to the same machine, but each domain name can refer to no more than one machine. Usually, all of the machines on a given Network will have the same thing as the right-hand portion of their Domain Names (matisse.net in the examples above). It is also possible for a Domain Name to exist but not be connected to an actual machine. This is often done so that a group or business can have an Internet e-mail address without having to establish a real Internet site. In these cases, some real Internet machine must handle the mail on behalf of the listed Domain Name.

DNS domain name system When you send email or point a browser to an Internet domain such as cnet.com, the domain name system translates the names into Internet addresses (a series of numbers looking something like this: 123.123.23.2). The term refers to two things: the conventions for naming hosts and the way the names are handled across the Internet.

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 (howeverr 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.

Ethernet A very common method of networking computers in a LAN. 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.

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.)

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-BaseTEthernet, about twice as fast as T-3).

firewall If you want to protect any networked server from damage (intentional or otherwise) by those who log in to it, you put up a firewall. This could be a dedicated computer equipped with security measures such as a dial-back feature, or it could be software-based protection called defensive coding.  A combination of hardware and software that separates a Network into two or more parts for security purposes.

FTP -- (File Transfer Protocol) 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.

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.
1000 or 1024 Megabytes, depending on who is measuring.

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).

hit As used in reference to the World Wide Web, hit means a single request from a web browser for a single item from a web server; thus in order for a web browser to display a page that contains 3 graphics, 4 hits would occur at the server: 1 for the HTML page, and one for each of the 3 graphics.

Host
Any computer on a network that is a repository for services available to other computers on the network. It is quite common to have one host machine provide several services, such as SMTP (email) and HTTP (web).

HTML
-- (HyperText Markup Language) The coding language used to create Hypertext documents for use on the World Wide Web. HTML looks a lot like old-fashioned typesetting code, where you surround a block of text with codes that indicate how it should appear.

The "hyper" in Hypertext comes from the fact that in HTML you can specify that a block of text, or an image, is linked to another file on the Internet. HTML files are meant to be viewed using a "Web Browser".

HTTP -- (HyperText Transfer Protocol) The protocol for moving hypertextfiles across the Internet. Requires a HTTP client program on one end, and an HTTP server program on the other end. HTTP is the most important protocol used in the World Wide Web (WWW).

Hypertext
Generally, any text that contains links to other documents - words or phrases in the document that can be chosen by a reader and which cause another document to be retrieved and displayed.

IMAP
-- (Internet Message Access Protocol) IMAP is gradually replacing POP as the main protocol used by email clients in communicating with email servers.

Using IMAP an email client program can not only retrieve email but can also manipulate message stored on the server, without having to actually retrieve the messages. So messages can be deleted, have their status changed, multiple mail boxes can be managed, etc.

Intranet A private network inside a company or organization that uses the same kinds of software that you would find on the public Internet, but that is only for internal use. Compare with extranet.

IP Number -- (Internet Protocol Number) Sometimes called a dotted quad. A unique number consisting of 4 parts separated by dots, e.g.

Every machine that is on the Internet has a unique IP number - if a machine does not have an IP number, it is not really on the Internet. Many machines (especially servers) also have one or more Domain Names that are easier for people to remember.

ISDN -- (Integrated Services Digital Network) Basically a way to move more dataover existing regular phone lines. ISDN is available to much of the USA and in most markets it is priced very comparably to standard analog phone circuits. It can provide speeds of roughly 128,000 bits-per-second over regular phone lines. In practice, most people will be limited to 56,000or 64,000 bits-per-second. Unlike DSL, ISDN can be used to connect to many different locations, one at a time, just like a regular telephone call, as long the other location also has ISDN.

ISP -- (Internet Service Provider) An institution that provides access to the Internet in some form, usually for money. Java Java is a network-friendly programming language invented by Sun Microsystems.

Java is often used to build large, complex systems that involve several different computers interacting across networks, for example transaction processing systems. Java is also becoming popular for creating programs that run in small electronic devicws, such as mobile telephones. A very common use of Java is to create programs that can be safely downloaded to your computer through the Internet and immediately run without fear of viruses or other harm to your computer or files. Using small Java programs (called "Applets"), Web pages can include functions such as animations,calculators, and other fancy tricks.

JavaScript JavaScript is a programming language that is mostly used in web pages, usually to add features that make the web page more interactive. When JavaScript is included in an HTML file it relies upon the browser to interpret the JavaScript. When JavaScript is combined with Cascading Style Sheets(CSS), and later versions of HTML (4.0 and later) the result is often called DHTML.

Kilobyte A thousand bytes. Actually, usually 1024 (210) bytes.

LAN -- (Local Area Network) A computer network limited to the immediate area, usually the same building or floor of a building.

Leased Line
Refers to line such as a telephone line or fiber-optic cable that is rented for exclusive 24-hour, 7-days-a-week use from your location to another location. The highest speed data connections require a leased line.

Linux
A widely used Open Source Unix-like operating system. Linux was first released by its inventor Linus Torvalds in 1991. There are versions of Linux for almost every available type of computer hardware from desktop machines to IBM mainframes. The inner workings of Linux are open and available for anyone to examine and change as long as they make their changes available to the public. This has resulted in thousands of people working on various aspects of Linux and adaptation of Linux for a huge variety of purposes, from servers to TV-recording boxes.Listserv The most common kind of maillist, "Listserv" is a registered trademark of L-Soft international, Inc. Listservs originated on BITNET but they are now common on the Internet. Login Noun or a verb. Noun: The account name used to gain access to a computer system. Not a secret (contrast with Password). Verb: the act of connecting to a computer system by giving your credentials (usually your "username" and "password")

Megabyte A million bytes. Actually, technically, 1024 kilobytes.

Modem -- (MOdulator, DEModulator) A device that connects a computer to a phone line. A telephone for a computer. A modem allows a computer to talk to other computers through the phone system. Basically, modems do for computers what a telephone does for humans. MOO -- (Mud, Object Oriented) One of several kinds of multi-user role-playing environments. Mosaic The first WWW browser that was available for the Macintosh, Windows,and UNIX all with the same interface. Mosaic really started the popularity of the Web. The source-code to Mosaic was licensed by several companies and used to create many other web browsers.

Mosaic was developed at the National Center for Supercomputing Applications (NCSA), at the Univeristy of Urbana-Champange in Illinois, USA. The first version was released in late 1993.

MUD -- (Multi-User Dungeon or Dimension) A (usually text-based) multi-user simulation environment. Some are purely for fun and flirting, others are used for serious software development, or education purposes and all thatlies in between. A significant feature of most MUDs is that users can create things that stay after they leave and which other users can interact within their absence, thus allowing a world to be built gradually and collectively. MUSE -- (Multi-User Simulated Environment) One kind of MUD - usually with little or no violence.

Network Any time you connect 2 or more computers together so that they can share resources, you have a computer network. Connect 2 or more networks together and you have an internet.

Newsgroup The name for discussion groups on USENET.

NIC
-- (Network Information Center) Generally, any office that handles information for a network. The most famous of these on the Internet was the InterNIC, which was where most new domain names were registered until that process was decentralized to a number of private companies. Also means "Network Interface card", which is the card in a computer that you plug a network cable into.

Packet Switching
The method used to move data around on the Internet. In packet switching,all the data coming out of a machine is broken up into chunks, each chunk has the address of where it came from and where it is going. This enables chunks of data from many different sources to co-mingle on the same lines, and be sorted and directed along different routes by special machines along the way. This way many people can use the same lines at the same time. You might think of several caravans of trucks all using the same road system. to carry materials.

ping To check if a server is running. From the sound that a sonar systems makes in movies, you know, when they are searching for a submarine.

PNG -- (Portable Network Graphics) PNG is a graphics format specifically designed for use on the World Wide Web. PNG enable compression of images without any loss of quality, including high-resolution images. Another important feature of PNG is that anyone may create software that works with PNG images without paying any fees - the PNG standard is free of any licensing costs.

POP
-- (Point of Presence, also Post Office Protocol) Two commonly used meanings:
Point of Presence and Post Office Protocol.  Post Office Protocol refers to a way that e-mail client software such as Eudora gets mail from a mail server. When you obtain an account from an Internet Service Provider (ISP) you almost always get a POP account with it, and it is this POP account that you tell your e-mail software to use to get your mail. Another protocol called IMAP is replacing POP for email.

Port 3 meanings. First and most generally, a place where information goes into or out of a computer, or both. E.g. the serial port on a personal computer is where a modem would be connected. On the Internet port often refers to a number that is part of a URL, appearing after a colon (:) right after the domain name. Every service on an Internet server listens on a particular port number on that server. Most services have standard port numbers, e.g. Web servers normally listen on port 80. Services can also listen on non-standard ports, in which case the port number must be specified in a URL when accessing the server, so you might see a URL of the form: This shows a gopher server running on a non-standard port (the standard gopher port is 70). Finally, port also refers to translating a piece of software to bring it from one type of computer system to another, e.g. to translate a Windows program so that is will run on a Macintosh.

Portal Usually used as a marketing term to described a Web site that is or is intended to be the first place people see when using the Web. Typically a "Portal site" has a catalog of web sites, a search engine, or both. A Portal site may also offer email and other service to entice people to use that site as their main "point of entry" (hence "portal") to the Web.

PPP -- (Point to Point Protocol) The most common protocol used to connect home computers to the Internet over regular phone lines.Most well known as a protocol that allows a computer to use a regular telephone line and a modem to make TCP/IPconnections and thus be really and truly on the Internet.

Proxy Server A Proxy Server sits in between a Client and the "real" Server that a Client is trying to use. Client's are sometimes configured to use a Proxy Server, usually an HTTP server. The clients makes all of it's requests from the Proxy Server, which then makes requests from the "real" server and passes the result back to the Client. Sometimes the Proxy server will store the results and give a stored result instead of making a new one (to reduce use of a Network). Proxy servers are commonly established on Local Area Networks

Router  A special-purpose computer (or software package) that handles the connection between 2 or more Packet-Switched networks. Routers spend all their time looking at the source and destination addresses of the packets passing through them and deciding which route to send them on.

SDSL
-- (Symmetric Digital Subscriber Line) A version of DSL where the upload speeds and download speeds are the same.

Security Certificate
A chunk of information (often stored as a text file) that is used by the SSL protocol to establish a secure connection. Server A computer, or a software package, that provides a specific kind of service to client software running on other computers. The term can refer to a particular piece of software, such as a WWW server, or to the machine on which the software is running, e.g. "Our mail server is down today, that's why e-mail isn't getting out."

A single server machine can (and often does) have several different server software packages running on it, thus providing many different servers to clients on the network.

SLIP -- (Serial Line Internet Protocol) A standard for using a regular telephone line (a serial line) and a modem to connect a computer as a realInternet site. SLIP has largely been replaced by PPP. SMDS -- (Switched Multimegabit Data Service) A standard for very high-speed data transfer.
SMTP -- (Simple Mail Transfer Protocol) The main protocol used to send electronic mail from server to server on the Internet. SMTP is defined in RFC 821 and modified by many later RFC's

SNMP -- (Simple Network Management Protocol) A set of standards for communication with devices connected to a TCP/IP network. Examples of these devices include routers, hubs, and switches.

Spam (or Spamming) An inappropriate attempt to use a mailing list, or USENET or other networked communications facility as if it was a broadcast medium (which it is not) by sending the same message to a large number of people who didn?t ask for it. The term probably comes from a famous Monty Python skit which featured the word spam repeated over and over. The term may also have come from someone?s low opinion of the food product with the same name, which is generally perceived as a generic content-free waste of resources. (Spam is a registered trademark of Hormel Corporation, for its processed meat product.)

SQL
-- (Structured Query Language) A specialized language for sending queries to databases. Most industrial-strength and many smaller database applications can be addressed using SQL. Each specific application will have its own slightly different version of SQL implementing features unique to that application, but all SQL-capable databases support a common subset of SQL.

SSL -- (Secure Socket Layer) A protocol designed by Netscape Communications to enable encrypted, authenticated communications across the Internet.
Sysop -- (System Operator) Anyone responsible for the physical operations of a computer system or network resource. For example, a System Administrator decides how often backups and maintenance should be performed and the System Operator performs those tasks.

T1
If ISDN isn't enough digital carrier for you, T1 offers faster speeds. T1 is a term coined by AT&T for a system that transfers digital signals at 1.544 megabits per second (as opposed to ISDN's mere 64 kilobits per second). Of course, if T1 doesn't cut it, there's always T3. (T2 seems to have been bypassed altogether.)

T-3 Aleased-line connection capable of carrying data at 44,736,000 bits-per-second. This is more than enough to do full-screen, full-motionvideo. When you're transferring data across a digital carrier, T3 is the premium way to go. It's not just three times the capacity of T1, as the name suggests--it's almost 30 times the capacity. It can handle 44.736 megabits of digital data per second.

TCP/IP -- (Transmission Control Protocol/Internet Protocol) This is the suiteof protocols that defines the Internet. Originally designed for the UNIX operating system, TCP/IP software is now included with every major kind of computer operating system. To be truly on the Internet, your computer must have TCP/IP software. The command and program used to login from one Internet siteto another. The telnet command/program gets you to the login: prompt of another host.

Terabyte 1000 gigabytes.

Terminal A device that allows you to send commands to a computer somewhere else. At a minimum, this usually means a keyboard and a display screen and some simple circuitry. Usually you will use terminal software in a personal computer - the software pretends to be (emulates) a physical terminal and allows you to type commands to a computer somewhere else.
Terminal Server A special purpose computer that has places to plug in many n modemsoone side, and a connection to a LAN or host machine onthe other side. Thus the terminal server does the work of answering thecalls and passes the connections on to the appropriate node. Mostterminal servers can provide PPP or SLIP services if connectedto the Internet.

TLD -- (Top Level Domain) The last (right-hand) part of a complete Domain Name. For example in the domain name www.matisse.net ".net" is the Top Level Domain. There are a large number of TLD's, for example .biz, .com, .edu, .gov, .info, .int, .mil, .net, .org, and a collection of two-letter TLD's corresponding to the standard two-letter country codes, for example, .us, .ca, .jp, etc.

USB universal serial bus Imagine replacing all those ports on the back of your PC--mouse, keyboard, serial, parallel, joystick, and more--with a single port. Now imagine you can daisy-chain as many as 127 peripherals off that port and use them all at once. Finally, imagine that the port supports data transfer rates up to 12MB/sec, making it suitable for even high-bandwidth applications such as video. Imagine no more. USB--designed by a consortium of PC manufacturers including Compaq, Digital, and IBM--can do all this and more.

URL -- (Uniform Resource Locator) The term URL is basically synonymous with URI. URI has replaced URL in technical specifications.

URN -- (Uniform Resource Name) A URI that is supposed to be available for along time. For an address to be a URN some institution is supposed to make a commitment to keep the resource available at that address.

USENET A world-wide system of discussion groups, with comments passed among hundreds of thousands of machines. Not all USENET machines are on the Internet. USENET is completely decentralized, with over 10,000 discussion areas, called newsgroups.

Virus
A chunk of computer programming code that makes copies of itself without any concious human intervention. Some viruses do more than simply replicate themselves, they might display messages, install other software or files, delete software of files, etc.

A virus requires the presence of some other program to replicate itself. Typically viruses spread by attaching themselves to programs and in some cases files, for example the file formats for Microsoft word processor and spreadsheet programs allow the inclusion of programs called "macros" which can in some cases be a breeding ground for viruses. VPN -- (Virtual Private Network) Usually refers to a network in which some of the parts are connected using the public Internet, but the data sent across the Internet is encrypted, so the entire network is virtually private.

WAIS -- (Wide Area Information Servers) A commercial software package that allows the indexing of huge quantities of information, and then making those indices searchable across networks such as the Internet. A prominent feature of WAIS is that the search results are ranked (scored) accordingto how relevant the hits are, and that subsequent searches can find more stuff like that last batch and thus refine the search process.

WAN
-- (Wide Area Network) Any internet or network that covers an area larger than a single building or campus.Web Short for "World Wide Web."

Worm A worm is a virus that does not infect other programs. It makes copies of itself, and infects additional computers (typically by making use of network connections) but does not attach itself to additional programs; however a worm might alter, install, or destroy files and programs.

XML
-- (eXtensible Markup Language) A widely used system for defining data formats. XML provides a very rich system to define complex documents and data structures such as invoices, molecular data, news feeds, glossaries, inventory descriptions, real estate properties, etc. As long as a programmer has the XML definition for a collection of data (often called a "schema") then they can create a program to reliably process any data formatted according to those rules.

| main | contact us | history of computers | computer tips |