Tech Tips: Browers and Computer Networking
AALL Conference; July 18th, 2000

Internet Terms

The Basics

LAN: Local Area Network: Geographically small collection of machines connected by a network. Another common definition says that a LAN is a network of machines separated by other portions of the network by a router.
Protocol: Formal specification of the rules of a network service or communication method
TCP/IP: Transmission Control Protocol/Internet Protocol: The most popular set of rules by which machines communicate across a network
Firewall: Hardware and/or software at the entrance to a network that controls what kind of traffic can be shared between hosts inside the network and the Internet.

Provide the foundation that everything else is build upon

DNS: Domain Name Service: Translates human-friendly domain names (e.g., "www.iii.com") to IP addresses (e.g., "205.227.88.232").
PPP: Point-to-Point Protocol: A method of connecting a computer to a network over a modem line.
ISDN: Integrated Services Digital Network: An enhanced type of telephone service where telephone conversations and data communications travel digitally between the subscriber and the phone company.
DSL: Digital Subscriber Line: Another telephone company invention to get even higher digital speeds out of the same phone line.
POP: Point of Presence: For an Internet Service Provider (ISP), a city or other location where a connection can be made to the network.

Actually get some work done

FTP: File Transfer Protocol: Used to transfer files between two machines.
HTTP: Hyper Text Transport Protocol: Specification for how web browsers communicate with web servers.
POP: Post Office Protocol: Protocol specifying how an e-mail client, such as Eudora or Outlook Express, would retrieve messages from a mail server.; The mail-store is on the client.
IMAP: Internet Message Access Protocol: Another protocol specifying how an e-mail client would retrieve messages from a server.; The mail-store is on the server.
SMTP: Simple Mail Transport Protocol: Protocol for sending electronic mail messages from one mail system to another.

This web thing will never catch on...

HTML: Hyper Text Markup Language: The page description language used to construct web pages.
URL: Uniform Resource Locator: The "address" of a resource on the net. Consists of three parts: the "protocol", the "hostname", and the machine- or protocol-specific information.
Cookie: A bit of information that a web server requests a web browser to store and echo back to the server for subsequent transations.
GIF: Graphics Interchange Format: One graphics format popularized by CompuServer which uses "lossless" compression, but limits the color depth
JPEG: Joint Photographic Experts Group: One graphics format which uses "lossy" compression, but has a much higher color depth

CGI: Common Gateway Interface: Specification for a web server to communicate with a program running on the web server.
Java: Network-oriented, machine-independent programming language designed by Sun Microsystems
JavaScript: Simple scripting language used to control web browser functions. Not related to Java.
Java Applet vs. Java Application: A "Java Applet" requires a web browser to provide a "framework" for the program. A "Java Application" stands alone (does not run inside a browser window).
Proxy: A network service with intercepts requests between a client and a server.

Process Layer	To aid in the understanding and in the evolution of networks, network specialists and software developers have defined a four-layer model to describe the network. Each layer is built on the foundation of the layer below.
Transport Layer
Network Layer
Data Link Layer

Process	Physical connectivity between machines This is the layer where the "wire" is. "Ethernet", "FDDI", "ATM", etc. Addressing: "Ethernet Address", etc. Equipment: Repeaters, Bridges, Switches
Transport
Network
Data Link

Process	Inter-machine Communication The "IP" of "TCP/IP" (Internet Protocol) Addressing: "IP Address" Equipment: Routers, Gateways
Transport
Network
Data Link

Process	End-to-End Communication Transmission Control Protocol (TCP) User Datagram Protocol (UDP) Addressing: "Port" Equipment: Firewalls, Proxies
Transport
Network
Data Link

Process	User Programs Telnet, WWW, FTP, etc.
Transport
Network
Data Link

Slides are available over the Internet at http://www.PandC.org/peter/presentations/aall2000/
Presenter Information

Peter Murray
Computer Services Librarian
University of Connecticut School of Law