INTERNET & COMPUTER GLOSSARY

Shown below is a fairly comprehensive list of internet and computer terms that are used when discussing technology. Become familiar with these terms if you want to better understand the terminology.

ADN (Advanced Digital Network)

Usually refers to a 56Kbps leased-line.

ADSL (Asymmetric Digital Subscriber Line)

A DSL line where the upload transmission rate is different from the download transmission rate. In most cases, the download speed is much greater.

APPLET

An applet is a small executable program, that usually doesn't have the complete features and user interface of a normal application. Java is the language most commonly associated with applets. An applet is like a small piece of executable code that needs a full application to contain it (usually a web browser). The applet runs inside of the application in a "sand box" or "virtual machine," which is a set of computer resources and instructions that make up an environment for the applet's execution.

ARPANet (Advanced Research Projects Agency Network)

The Internet basically evolved from early ground-breaking work on this project. 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.

ASP

Active Server Pages. A server side scripting language developed by Microsoft. This has recently been replaced by the dotNet version: "ASP.Net".

AUDIO STREAMING

Delivering audio content from your server in real time. This means that the consumer is downloading the audio stream while it is being played. Audio information is buffered on the local computer to take into account lagging network performance.

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

The transmission rate at which data can be transferred through an Internet connection. This is typically measured as bits-per-second. A full page of English text is about 16,000 bits. A fast modem can move about 15,000 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).

BBS (Bulletin Board System)

A web-based discussion forum that allows people to carry on conversations, 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.

BIT (Binary DigIT)

A single digit number in the base-2 numbering system. In other words, each digit can hold one of two values: either a 1 or a zero. This is the smallest unit of computerized data. Bandwidths are usually measured in bits-per-second.

BLOG (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." Blogs are typically updated daily using software that allows people with little or no technical background to update and maintain the blog.

Postings on a blog are almost always arranged in chronological order with the most recent additions featured most prominently.

BROWSER

A Client program (software) that is used to look at various kinds of Internet resources. The most popular applications are Internet Explorer and Netscape.

BYTE

A set of Bits that represent a single character (at least in RTF-8 encoding). Usually there are 8 Bits in a Byte, sometimes more, depending on how the measurement is being made.

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.

Usually a CGI program is a small program that takes data from a web server and does something with it, like putting the content of a form into an e-mail message, or turning the data into a database query. You can often see that a CGI program is being used by seeing "cgi-bin" in a URL, but not always.

CGI-BIN

A commonly-used directory on a web server from where CGI scripts are executed.

CO-LOCATION

Typically 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.

COMMAND-LINE INTERFACE

If you are familiar with the Windows DOS Command prompt or the Unix console, then you know exactly what a command-line interface is. It is a text-only interface to a computer where you type in commands and output is displayed in text characters only.

COOKIE

A piece of information given to a Web browser by a Web server. The browser stores the information in a text file called cookie.txt. The information is then sent back to the server each time the browser requests a page from the server.

The main purpose of cookies is to identify users and possibly prepare customized Web pages for them. When you enter a Web site using cookies, you may be asked to fill out a form providing such information as your name and interests. This information is packaged into a cookie and sent to your Web browser which stores it for later use. The next time you go to the same Web site, your browser will send the cookie to the Web server. The server can use this information to present you with custom Web pages. So, for example, instead of seeing just a generic welcome page you might see a welcome page with your name on it.

The name cookie derives from UNIX objects called magic cookies. These are tokens that are attached to a user or program and change depending on the areas entered by the user or program. Cookies are also sometimes called persistent cookies because they typically stay in the browser for long periods of time.

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.

Cookies do not read your hard drive and send your life story to the CIA, but they can be used to gather more information about a user than would be possible without them.

CSS (Cascading Style Sheet)

A standard for specifying the appearance of text and other elements on a web site. CSS was developed for use with HTML in Web pages but is also used in other situations, notably in applications built using XPFE. CSS is typically used to provide a single "library" of styles that are used over and over throughout a large number of related documents, as in a web site. A CSS file might specify that all numbered lists are to appear in italics. By changing that single specification the look of a large number of documents can be easily changed.

DATA TRANSFER

This is the amount of data that you are allowed to transfer with your account. Data is this case usually referrs to images, text, or anthing else that the web server must transfer to the user's web browser. As a general rule 500 MB of data transfer is equivilant to about 20,000 page views.

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:

• aspnut.com
• www.aspnut.com

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.

DOWNLOAD

Transferring data (usually a file) from a remote computer to the local computer that you are are using. This is the opposite of upload because data is being moved in the opposite direction.

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.

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.

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.

ETHERNET

A very common method of networking computers in a LAN. Refers to the physical wires (cables) that are used to network computers and (to a lesser extent) the communication protocol.

There is more than one type of Ethernet connection. 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 physically part of a company's 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.)

FAQ (Frequently Asked Questions)

FAQs are documents that list and answer the most common questions for 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.

FINGER

An Internet software tool that originated on Unix for locating people on other Internet sites. 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.

FIRE WALL

A combination of hardware and software that separates a Network into two or more parts for security purposes.

FRONT PAGE EXTENSIONS

A feature within Microsoft FrontPage that allows users to make use of the server side programming features of the web authoring tool. Its greatest use is the remote uploading of web content and generation of dynamic pages.

FTP (File Transfer Protocol)

A very common method of moving files between two Internet sites. FTP is a special way to login to another Internet site for the purposes of retrieving and/or sending files. There are many Internet sites that have established public archives of material that can be browsed using FTP and by logging in using the account name anonymous. These sites are called anonymous FTP servers

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.

GIGABYTE

A measurement of data storage consisting of 1000 or 1024 Megabytes, depending on who is measuring.

GUESTBOOK

A program, basically a form and database that keeps track of comments made by a visitor to a site.

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.

HOME PAGE (or Homepage)

Several meanings. Originally, the web page that your browser is set to use when it starts up. The more common meaning refers to the main web page for a business, organization, person or simply the main page out of a collection of web pages, e.g. "Check out so-and-so's new Home Page."

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). Another name for a "server".

HOSTING PROVIDER

An institution that provides web space to companies or individuals, usually for money.

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".

HTML is loosely based on a more comprehensive system for markup called SGML.

HTTP (HyperText Transport Protocol)

The protocol for moving hypertext files 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).

IP ADDRESS (Internet Protocol Number)

A unique number consisting of 4 parts separated by dots, e.g. 207.123.215.23. Each part is an individual byte with a value ranging from 0 to 255. This allows the entire address to be represented as a 4-byte integer (known as a word) consisting of 32 bits. 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. Most machines also have one or more Domain Names that are easier for people to remember.

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. IMAP is defined in RFC 2060

INTERNET (Upper case I)

The vast collection of inter-connected networks that are connected using the TCP/IP protocols and that evolved from the ARPANET of the late 60's and early 70's. The Internet connects tens of thousands of independent networks into a vast global internet and is probably the largest Wide Area Network in the world.

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.

IRC (Internet Relay Chat)

Basically a huge multi-user live chat facility. There are a number of major IRC servers around the world which are linked to each other. Anyone can create a channel and anything that anyone types in a given channel is seen by all others in the channel. Private channels can (and are) created for multi-person conference calls.

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. The most common connection protocols are by using a "dial-up modem", DSL (Direct Subscriber Line) or a "cable modem".

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 measurement of data storage consisting of a thousand bytes. This is actually 1024 bytes which is a round number in the base 2 numbering scheme (2¹⁰).

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.

LOCAL/REMOTE COMPUTER

The local computer is the one client uses. Or in relation to you, it is the computer that is right in front of you. A remote computer is one found in a remote location. You connect to a remote computer using your web browser to view a web site.

MAILLIST (or Mailing List)

A (usually automated) system that allows people to send e-mail to one address, whereupon their message is copied and sent to all of the other subscribers to the maillist. In this way, people who have many different kinds of e-mail access can participate in discussions together.

MEGABYTE

A measurement of storage consisting of one million bytes. Actually, technically, 1024 kilobytes

MIRROR

Generally speaking, "to mirror" is to maintain an exact copy of something. Probably the most common use of the term on the Internet refers to "mirror sites" which are web sites, or FTP sites that maintain copies of material originated at another location, usually in order to provide more widespread access to the resource. For example, one site might create a library of software, and 5 other sites might maintain mirrors of that library.

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.

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.

NNTP (Network News Transport Protocol)

The protocol used by clientand server software to carry USENET postings back and forth over a TCP/IP network. If you are using any of the more common software such as Netscape, Nuntius, Internet Explorer, etc. to participate in newsgroups then you are benefiting from an NNTP connection.

PASSWORD

A code used to gain access (login) to a locked system. Good passwords contain letters and non-letters and are not simple combinations such as virtue7. A good password might be:

    6abq-1co

But don't be foolish enough to use this one!

PDF (Portable Document Format)

A file format designed to enable printing and viewing of documents with all their formatting (typefaces, images, layout, etc.) appearing the same regardless of what operating system is used, so a PDF document should look the same on Windows, Macintosh, linux, OS/2, etc. The PDF format is based on the widely used Postcript document-description language. Both PDF and Postscript were developed by the Adobe Corporation.

PERL

Practical Extraction and Report Language. A server side scripting language used to create dynamic and interactive web content.

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.

POP (Post Office Protocol)

A protocol used by a mail client to retrieve e-mail from a mail server. Most e-mail applications (sometimes called an e-mail client) use the POP protocol, although some can use the newer IMAP (Internet Message Access Protocol).

There are two versions of POP. The first, called POP2, became a standard in the mid-80's and requires SMTP to send messages. The newer version, POP3, can be used with or without SMTP.

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/IP connections and thus be really and truly on the Internet.

PROTOCOL

On the Internet "protocol" usually refers to a set of rules that define an exact format for communication between systems. For example the HTTP protocol defines the format for communication between web browsers and web servers, the IMAP protocol defines the format for communication between IMAP email servers and clients, and the SSL protocol defines a format for encrypted communications over the Internet.

Virtually all Internet protocls are defined in RFC documents.

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

RAW ACCESS DATA

Server data that can be downloaded and manipulated by a statistics program to provide meaningful information about a website traffic.

RFC (Request For Comments)

The name of the result and the process for creating a standard on the Internet. New standards are proposed and published on the Internet, as a Request For Comments. The proposal is reviewed by the Internet Engineering Task Force (http://www.ietf.org/), a consensus-building body that facilitates discussion, and eventually a new standard is established, but the reference number/name for the standard retains the acronym RFC, e.g. the official standard for e-mail message formats is RFC 822.

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

RSS (Rich Site Summary or RDF Site Summary or Real Simple Syndication)

A commonly used protocol for syndication and sharing of content, originally developed to facilitate the syndication of news articles, now widely used to share the contents of blogs.

RSS is an XML-based summary of a web site, usually used for syndication and other kinds of content-sharing.

There are RSS "feeds" which are sources of RSS information about web sites, and RSS "readers" which read RSS feeds and display their content to users.

RSS is being overtaken by a newer, more complex protocol called Atom.

SDSL (Symmetric Digital Subscriber Line)

A version of DSL where the upload speeds and download speeds are the same.

SEARCH ENGINE

A (usually web-based) system for searching the information available on the Web.

Some search engines work by automatically searching the contents of other systems and creating a database of the results. Other search engines contains only material manually approved for inclusion in a database, and some combine the two approaches.

SEO (Search Engine Optimization)

The practice of designing web pages so that they rank as high as possible in search results from search engines.

There is "good" SEO and "bad" SEO. Good SEO involves making the web page clearly describe its subject, making sure it contains truly useful information, including accurate information in Meta tags, and arranging for other web sites to make links to the page. Bad SEO involves attempting to deceive people into believing the page is more relevant than it truly is by doing things like adding inaccurate Meta tags to the page.

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 could have several different server software packages running on it, thus providing many different servers to clients on the network.

SERVER SIDE INCLUDES (SSI)

Commands that can be included in web pages that are processed by the web server when a user requests a file. The command takes the form:

  <!--#include virtual="/path/to/file"-->

For example, a common use for SSI commands is to insert the date or last modified date on a file.

SMTP (Simple Mail Transport Protocol)

The main protocol used to send electronic mail on the Internet.

SMTP consists of a set of rules for how a program sending mail and a program receiving mail should interact.

Almost all Internet email is sent and received by clients and servers using SMTP, thus if one wanted to set up an email server on the Internet one would look for email server software that supports SMTP.

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.

SNMP is defined in RFC 1089

SOAP (Simple Object Access Protocol)

A protocol for client-server communication that sends and receives information "on top of" HTTP. The data sent and received is in a particular XML format specifically designed for use with SOAP. SOAP is similar to the XMLRPC protocol except that SOAP provides for more sophisticated handling of complex data being sent between a client and a server. SOAP actually grew from the work that created XMLRPC.

Microsoft's ".NET" system is largely based on SOAP.

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. (SpamŽ is a registered trademark of Hormel Corporation, for its processed meat product.)

SPYWARE

A somewhat vague term generally referring to software that is secretly installed on a users computer and that monitors use of the computer in some way without the users' knowledge or consent.

Most spyware tries to get the user to view advertising and/or particular web pages. Some spyware also sends information about the user to another machine over the Internet.

Spyware is usually installed without a users' knowledge as part of the installation of other software, especially software such as music sharing software obtained via download.

SSL (Secure Sockets Layer)

A protocol designed by Netscape Communications to enable encrypted, authenticated communications across the Internet.

SSL used mostly (but not exclusively) in communications between web browsers and web servers. URL's that begin with "https" indicate that an SSL connection will be used.

SSL provides 3 important things: Privacy, Authentication, and Message Integrity.

In an SSL connection each side of the connection must have a Security Certificate, which each side's software sends to the other. Each side then encrypts what it sends using information from both its own and the other side's Certificate, ensuring that only the intended recipient can de-crypt it, and that the other side can be sure the data came from the place it claims to have come from, and that the message has not been tampered with.

T-1

A leased-line connection capable of carrying data at 1,544,000 bits-per-second. At maximum theoretical capacity, a T-1 line could move a megabyte in less than 10 seconds. That is still not fast enough for full-screen, full-motion video, for which you need at least 10,000,000 bits-per-second. T-1 is the fastest speed commonly used to connect networks to the Internet.

T-3

A leased-line connection capable of carrying data at 44,736,000 bits-per-second. This is more than enough to do full-screen, full-motion video.

TCP/IP (Transmission Control Protocol/Internet Protocol)

This is the suite of 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.

TELNET

An Internet Protocol for doing a terminal session from one computer (your local computer) to a remote computer (the remote host). Commonly used on Unix-based systems which use a command-line interface for managing the services.

TERABYTE

A measurement of storage consisting of 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.

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.

TROJAN HORSE

A computer program is either hidden inside another program or that masquerades as something it is not in order to trick potential users into running it. For example a program that appears to be a game or image file but in reality performs some other function. The term "Trojan Horse" comes from a possibly mythical ruse of war used by the Greeks sometime between 1500 and 1200 B.C.

A Trojan Horse computer program may spread itself by sending copies of itself from the host computer to other computers, but unlike a virus it will (usually) not infect other programs.

UNIX

A computer operating system (the basic software running on a computer, underneath things like word processors and spreadsheets). UNIX is designed to be used by many people at the same time (it is multi-user) and has TCP/IP built-in. It is the most common operating system for servers on the Internet.

URL (Uniform Resource Locator) or URI (Uniform Resource Identifier) The standard way to give the address of any resource on the Internet that is part of the World Wide Web (WWW). A URL looks like this:

http://www.aspnut.com/index.asp

The most common way to use a URL is to enter into a WWW browser program, such as Internet Explorer, or Netscape.

UPLOAD

Transferring data (usually a file) from a the computer you are using to another computer. The opposite of download.

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.

VIDEO STREAMING

The process of providing video data or content via a web page.

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.

WAN (Wide Area Network)

Any internet or network that covers an area larger than a single building or campus.

WEB PAGE

A document designed for viewing in a web browser. Typically written in HTML. A web site is made of one or more web pages.

WEB SITE

A collection of web resources such as HTML pages, CGI scripts, images, audio and video files that are grouped together in a common location. With the help of a web server such as IIS (Internet Information Server) or Apache, the resources are made available to the world with the use of a web browser.

WEBMASTER

A person whose role is to design, build and maintain a web site.

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.

WWW (World Wide Web)

World Wide Web (or simply Web for short) is a term frequently used (incorrectly) when referring to "The Internet", WWW has two major meanings: First, loosely used: the whole constellation of resources that can be accessed using Gopher, FTP, HTTP,telnet, USENET, WAIS and some other tools. Second, the universe of hypertext servers (HTTP servers), more commonly called "web servers", which are the servers that serve web pages to web browsers.