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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.

See also: Download, DSL, SDSL, Upload

Anonymous FTP

See also: FTP

Application Server
Server software that manages one or more other pieces of software in a way that makes the managed software available over a network, usually to a Web server. By having a piece of software manage other software packages it is possible to use resources like memory and database access more efficiently than if each of the managed packages responded directly to requests.

See also: Server


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.

See also: Network


How much stuff you can send through a connection. Usually measured in bits-per-second (bps.) 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.

See also: Bit, T-1

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.

See also: Bandwidth, T-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.


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.

DHCP (Dynamic Host Configuration Protocol)

DHCP is a protocol by which a machine can obtain an IP number (and other network configuration information) from a server on the local network.

DNS (Domain Name System)

The Domain Name System is the system that translates Internet domain names into IP numbers. A "DNS Server" is a server that performs this kind of translation.

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

See also: Upload

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.

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.

See also: WWW


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.

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 (such as Apache) on the other end. HTTP is the most important protocol used in the World Wide Web (WWW).

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.

See also: Client, Server, WWW


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 used to create software with graphical user interfaces such as editors, audio players, web browsers, etc.

Java is also popular for creating programs that run in small electronic devicws, such as mobile telephones.

Using small Java programs (called "Applets"), Web pages can include functions such as animations,calculators, and other fancy tricks.

LAN (Local Area Network)

A computer network limited to the immediate area, usually the same building or floor of a building.

See also: WAN, 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.

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.


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:

exm://dhecyber:xxxx [ex. 7000]
This shows a exm 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.

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

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.

See also: Packet Switching

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

See also: ADSL, DSL


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.

Sometimes server software is designed so that additional capabilities can be added to the main program by adding small programs known as servlets.

See also: Client, Network, Servlet


A small computer program designed to be add capabilities to a larger piece of server software.

Common examples are "Java servlets", which are small programs written in the Java language and which are added to a web server. Typically a web server that uses Java servlets will have many of them, each one designed to handle a very specific situation, for example one servlet will handle adding items to a "shopping cart", while a different servlet will handle deleting items from the "shopping cart."

See also: Java, Server, Web


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 lines are commonly used to connect large LANs to theInternet.

See also: 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-motionvideo.

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

See also: Download

WAN (Wide Area Network)

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

See also: LAN

Short for "World Wide Web."

See also: WWW

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.

See also: HTTP, Server