Most people who use the Internet for work or play don't need to understand the guts of how the Internet works. Many have learned Internet buzzwords by word-of-mouth, and the precise meanings of the terms can get garbled.

This glossary tries to point out common misusages of Internet terms. Frequently adulterated definitions are marked with the scarlet letter [A] (with apologies to Nathaniel Hawthorne). You will sound more like you know what you are talking about if you avoid them.

A bit of free advice. If you hear someone abusing one of these terms, consider how they might react if you correct them. You might find it better to just smile knowingly and nod.

browser

A program for looking at things such as World Wide Web pages.

DNS

Domain Name Service. A mechanism for translating a mnemonic name into an IP address.

file server

A computer which stores files on behalf of other computers in a network.

FTP

File Transfer Protocol. A protocol for transferring files from one computer to another. Also, usually written in lower case, a program which implements the protocol. FTP uses TCP to make the connection.

HTML

Hypertext Markup Language. A language for indicating how text is to be presented typographically to the reader, and including cross-references and graphical images.

HTTP

Hypertext Transfer Protocol. A protocol for transferring files, especially HTML files and associated images, from one computer to another. The World Wide Web's mechanism for transferring information between a server and a browser. HTTP uses TCP to make the connection.

ICMP

Internet Control Message Protocol. Part of the guts of IP. ICMP uses IP for routing.

interface

A device for connecting a computer to a network. Ethernet and token ring adapters are examples. On a personal computer it is sometimes called a Network Interface Card, or NIC.

Internet

A loose confederation of computer networks around the world. Any computer on the Internet can offer a service to any other computer, as long as they agree on the protocol.
[A] Don't confuse the Internet with the World Wide Web, which is only one of its services.

intranet

A confederation of networks inside an organization, such as a corporation.
[A] Your corporate intranet is probably much more than just a Web server, even if your internal corporate Web server is named "intranet."

IP

Internet Protocol. A protocol for routing messages between networks. IP is the fundamental protocol of the Internet.

IP address

A unique 32-bit number by which IP refers to each interface on the Internet. The number is usually written as four decimal numbers in the range 0-255, separated by periods. The left parts of the address identify the network and the right parts identify the interface in the network.
[A] Note that the address refers to the interface, not the computer. If a computer has more than one interface, each one will usually have its own address. This concept is key to understanding routers. If a computer has only one interface, you can safely pretend that its IP address is the address of the computer.

network

A confederation of computers and the equipment which lets them communicate.
[A] Many small office networks consist of a single file server and its clients. Don't confuse the file server with the network. When someone refers to a file as being "on the net," they probaby mean it's on a file server.

ping

A program which exchanges ICMP messages to verify that the network is operating.

protocol

A style of messages with which two or more computer programs agree to communicate. The programs are usually on different computers. Frequently several protocols are used together, building capabilities on top of others like the layers of an onion. For example, FTP is built around TCP, which is in turn built around IP.

router

A computer which implements IP to send messages from one network to another.

server

A computer which offers a service to other computers in a network.

TCP/IP

Transmission Control Protocol and Internet Protocol.
[A] Used broadly to refer to a collection of related software, including a suite of protocols and common programs such as ftp and telnet.

TCP

Transmission Control Protocol. A protocol to establish and maintain a long-term connection between programs. TCP uses positive acknowledgements and timers to guarantee delivery of data streams on both directions. TCP uses IP for routing.

telnet

A program which presents a command-line session on a remote computer. Telnet uses TCP to make the connection.

UDP

User Datagram Protocol. A protocol for sending individual messages between programs. UDP makes no promises about delivery, but it has lower overhead than TCP for infrequent messages. UDP uses IP for routing.

URL

Uniform Resource Locator. The name of some piece of information on the World Wide Web. It has several optional parts separated by specific punctuation marks:

1. a protocol name, such as http, followed by a colon;
2. a computer name preceeded by two slashes and followed by a slash;
3. a directory name followed by a slash;
4. a file name; and
5. a query preceeded by a question mark. Whew!

WWW

World Wide Web. A loose confedereration of computers on the Internet offering cross-referenced text, graphics, and other information. Even though the Web was invented late in the development of the Internet, it has become one of its most popular services.