AS: Autonomous System
Autonomous System: A collection of gateways (routers) under a single administrative authority using a common Interior Gateway Protocol for routing packets.

BANDWIDTH: The amount of data that can be transferred across telephone or network wires. Larger bandwidth means more information can be transferred at one time.

BAUD: When transmitting data, the number of times the medium's "state" changes per second.

BIT: BInary digiT
The smallest amount of information which may be stored in a computer.

BPS: Bits Per Second
Bits per second: A measure of data transmission speed.

BYTE: One character of information, usually eight bits wide.

DATAGRAM: The unit transmitted between a pair of Internet modules. The Internet Protocol provides for transmitting blocks of data, called datagrams, from sources to destinations.

DNS: Domain Name Server
A mechanism used in the Internet for translating names of host computers into addresses. The DNS also allows host computers not directly on the Internet to have registered names in the same style.

GATWEWAY: A special-purpose dedicated computer that attaches to two or more networks and routes packets from one network to the other. In particular, an Internet gateway routes IP datagrams among the networks it connects. Gateways route packets to other gateways until they can be delivered to the final destination directly across one physical network. See router.

HOST NUMBER: The part of an Internet address that designates which node on the (sub)network is being addressed.

INTERNET ADDRESS: An assigned number which identifies a host in an internet. It has two or three parts: network number, optional subnet number, and host number.

IP: Internet Protocol
The network layer protocol for the Internet. It is the datagram protocol defined by RFC 791.

ISDN: Integrated Services Digital Network
A telecommunications standard that allows for wide bandwidth digital transmission. It supports video, voice, and data transmissions over regular telephone lines at 64 kilobits of digital data per second.

PACKET: The unit of data sent across a packet switching network. The term is used loosely. While some Internet literature uses it to refer specifically to data sent across a physical network, other literature views the Internet as a packet switching network and describes IP datagrams as packets.

PPP: Point-to-Point Protocol
Provides a method for transmitting datagrams over serial point-to-point links.

PROTOCOL: A formal description of message formats and the rules two computers must follow to exchange those messages. Protocols can describe low-level details of machine-to-machine interfaces (e.g., the order in which bits and bytes are sent across a wire) or high-level exchanges between allocation programs (e.g., the way in which two programs transfer a file across the Internet).

ROUTER: A special-purpose dedicated computer that attaches to two or more networks and routes packets from one network to the other. In particular, an Internet gateway routes IP datagrams among the networks it connects. Gateways route packets to other gateways until they can be delivered to the final destination directly across one physical network.

SLIP: Serial Line Internet Protocol
SLIP is currently a de facto standard, commonly used for point-to-point serial connections running TCP/IP. It is not an Internet standard but is defined in RFC 1055.

SMTP: Simple Mail Transfer Protocol:
The Internet standard protocol for transferring electronic mail messages from one computer to another. SMTP specifies how two mail systems interact and the format of control messages they exchange to transfer mail.

SUBNET: A portion of a network, which may be a physically independent network, which shares a network address with other portions of the network and is distinguished by a subnet number. A subnet is to a network what a network is to an internet.

SUBNET NUMBER: A part of the Internet address which designates a subnet. It is ignored for the purposes of Internet routing, but is used for intranet routing.

TCP: Transmission Control Protocol
A transport layer protocol for the Internet. It is a connection-oriented, stream protocol defined by RFC 793.

TCP/IP: Transmission Control Protocol/Internet Protocol
Transmission Control Protocol/Internet Protocol: This is a common shorthand which refers to the suite of application and transport protocols which run over IP. These include FTP, Telnet, SMTP, and UDP (a transport layer protocol).

URL: Uniform Resource Locator
The address system for the World Wide Web. The URL contains information about the method of access, the server to be accessed, and the path of any file to be accessed.

X.25: A data communications protocol developed to describe how data passes into and out of public data communications networks. The public networks such as Telenet and Tymnet use X.25 to interface to customer computers.