Web Terminology Glossary

This glossary defines some of the terms commonly used by the World Wide Web. Note that many terms presented here may be used interchangeably. Other terms may have multiple meanings, depending on their context.

Definitions

anonymous ftp

See ftp server.

author

To author content for a web server, CDROM, or other medium, is to create or originate text, movies, images, and other material to be delivered in that medium.

authoring tools

The software programs or applications that aid in the creation of content including, but not limited to, text editors, word processors, movie/video/audio recording and editing software, image processing applications.

bastion host

Another term for a firewall.

browser

A software application that permits viewing and possibly searching of content, typically text, static images, or graphics, in a random or leisurely fashion at the user's discretion. As opposed to a player. See also viewer.

Cisco Systems

Cisco Systems manufacturers network routers.

client

A software application that makes requests of a server application for information or tasks to be executed by the server on behalf of the client. Clients and servers communicate via specialized protocols. Clients and servers can execute on different hosts on a network and these hosts can be very different computers.

content

The text, images, movies, audio, video, software, or other material contained in and delivered by media such as paper, CDROM, web server, video-on-demand, and so forth.

content authoring

The process or act of creating content to be delivered via a medium or multiple media.

dual-homed host

A type of firewall that uses two separate network connections, one to an internal network and the other to the Internet. This type of firewall doesn't allow data to pass directly between the two connections.

firewall

A system or set of systems through which all traffic between an internal network and an external network (usually the Internet) must pass. The firewall allows only authorized traffic to continue to the other side, where "authorized" is defined by the firewall-owner's security policy. Firewalls come in three types: packet filtering (usually implemented with a screening router), circuit gateways, and application gateways (usually implemented with a dual-homed host and proxy servers).

ftp

ftp is the text-based client software application for interactively transferring files between systems on the Internet via FTP. ftp is bundled with the workstations provided by Silicon Graphics.

FTP

Acronym for File Transfer Protocol. FTP is a networking protocol for moving files between machines. The client software application used in FTP transactions is either ftp or a web browser. The server software application for FTP transactions is ftpd.

ftp server

A server providing access to a collection of files for downloading via FTP. This is usually provided via an anonymous ftp account which requires the ftp user to enter the login name of anonymous.

ftp site

The primary ftp server on the Internet for an entity such as a company, university, organization, or other institution. The term ftp site does not usually refer to a ftp server on an internal LAN. Many sites on the Internet have adopted the naming convention of using the hostname or hostname alias ftp to denote the primary ftp server as in the domain name ftp.sgi.com.

gateway

A machine or set of machines used to relay packets from one network to another network. See also router.

GIF

GIF is the CompuServe(TM) Graphics Interchange Format for image files.

home page

An HTML page that is the primary or index document representing an entity such as a company or individual. The home page is usually the first page a client user receives from a web server and as such serves as an introduction to the entity or content being served. The home page for a server is typically named index.html and is the default page served if no path is specified in an HTTP protocol URL such as http://www.sgi.com/.

host

A node computer on a network. The etymology of the term host may be from the days when a computer on a network hosted multiple users and services.

HTML

Acronym for Hyper Text Markup Language.

HTML page

A single file document written in HTML. Although this page may require multiple pages of paper if printed, it is typically viewed as a single scrolled page in a web browser.

HTTP

Acronym for Hyper Text Transfer Protocol. HTTP is a networking protocol for retrieving HTML documents. The client software application used in HTTP transactions is a web browser. The server software application for HTTP transactions is ftpd.

Internet

An internet is a network of networks. The phrase "the Internet" loosely refers to the collection of all the linked networks in the world.

IP

Acronym for Internet Protocol, a low-level protocol that determines how packets are constructed for transmission over the Internet.

IRC

Acronym for Internet Relay Chat, software that allows Internet users to connect to central servers and send messages. Anything typed by one connected user is seen by all other connected users.

ISP

Acronym for Internet Service Provider, a general term for any company that provides a connection to the Internet for individuals or businesses.

JPEG

Acronym for Joint Photographic Experts Group. JPEG is a lossy compression scheme based on psycho-visual studies of human perception. Picture information that is generally not noticeable is dropped out in varying amounts. The result is that the file is reduced anywhere from 2 to 100 times its original size.

LAN

Acronym for Local Area Network, meaning a network in which all the hosts are in close physical proximity (roughly, within the same building or set of adjacent buildings).

lossy

A video/image compression method that doesn't preserve 100% of the information in the original data.

mailcap

The mailcap file provides a mapping from MIME content-type to viewers and players capable of viewing the corresponding content. This mapping is used by mail programs and web browsers to view many different kinds of content.

MIME

Acronym for Multipurpose Internet Mail Extensions. MIME is the official proposed standard format for extended Internet electronic mail. The MIME format permits e-mail to include enhanced text, graphics, audio, and more, in a standardized and interoperable manner. MIME compliant e-mail uses strings of characters in a mail message to delineate and denote various types of content within the message. HTTP uses MIME style content-type designations to inform the web browser of the content-type returned by the web server. See also mailcap.

Mosaic

See NCSA Mosaic.

MPEG

Acronym for Motion Pictures Expert Group. The MPEG standard, most often used for CDROM and World Wide Web authoring material) compression typically reduces the data size of an uncompressed file by a factor of 100. It is a lossy algorithm that is capable of producing higher compression ratios than JPEG and Cinepak compression schemes. The compressed data stream is designed so that the video can be played forward or backward. This makes MPEG well suited for video publishing, where a video is compressed once and decompressed many times for playback.

NCSA Mosaic

One of the first graphical web browsers, developed at NCSA.

Netscape Communications

The company started by Silicon Graphics founder Jim Clark and NCSA Mosaic chief engineer Marc Andreesen. Their primary products are a graphical web browser called Netscape Navigator(TM) (sometimes known simply as Netscape), and HTTP server software named Netscape Communications Server(TM).

Netscape Navigator(TM)

The graphical web browser developed by Netscape Communications.

Netscape Communications Server(TM)

The HTTP server software developed by Netscape Communications.

packet

A contiguous sequence of bits or bytes comprising all or part of a message communicated on a network.

player

A software application that permits viewing or playback of content such as audio, video, or movie files in primarily a linear fashion, although random indexing or control of playback may be permitted. As opposed to a browser. See also viewer.

PPP

Acronym for Point-to-Point Protocol. A protocol for making IP connections over a telephone line. A replacement for SLIP.

protocol

An agreed upon sequence of bits, bytes, or characters exchanged between programs for purposes of transmitting and receiving information. The most common context for use of the term protocol is in the area of computer networking. Common protocols include: FTP, HTTP.

proxy server

Software that runs on a firewall host and transmits information (usually from certain applications or types of applications) past the firewall in both directions. It's a server because it responds to requests from clients, and it's a proxy because it acts in place of the external server that the client is actually trying to reach.

router

A machine that forwards packets from one network to another. A gateway is a router. The term router often refers to a dedicated machine that performs packet forwarding and possibly packet filtering as opposed to a gateway, which may also be a network host. See also Cisco.

screening router

A router that provides filtering of network packets. Packet filtering prevents internal network packets from being leaked to an outside network such as the Internet, and prevents unwanted network packets from an external network from infiltrating an internal network. This filtering mechanism prevents outside attackers from gaining access to an internal network by rejecting the packets from the protocols outsiders would use to gain access to the internal network.

server

1. A software application that responds with requested information or executes tasks on the behalf of a client application. Clients and servers communicate via specialized protocols. Clients and servers may execute on different hosts on a network and these hosts may be very different computers. 2. A network host running a set of protocol server applications: an NFS server, an ftp server, a web server.

service provider

A company that provides Internet access. For end users, this service can be as simple as providing Internet e-mail accounts, access to Usenet news groups, ftp, and web browser access via the service provider's servers. A service provider can also provide a way for connecting an enterprise's LAN to the Internet allowing an enterprise to place their own servers on the Internet.

SGML

Acronym for Standard Generalized Markup Language.

SLIP

Acronym for Serial Line Internet Protocol. A protocol for sending IP packets over serial lines, such as telephone lines. Supplanted by PPP.

SOCKS

Originally short for "sockets." A software package that allows hosts behind a firewall to connect to the Internet.

tag

A character sequence in HTML and SGML that encodes the structural relationship of a sequence of text in a document. A tag is usually denoted as <tag>, which marks the beginning of a sequence of text of a specific type and </tag>, which marks the end of the sequence. The definition for interpreting the tags is determined by the Document Type Definition (DTD) used by HTML or SGML.

TIS(TM)

Acronym for Trusted Information Systems, Inc., a company that supplies software and support for firewall security.

URL

Acronym for Universal Resource Locator. A URL is a sequence of characters used to denote the means for retrieving a specific document or a piece of content from a server on the Web. The typical URL consists of three parts:

• The protocol used to retrieve the content.
• The name of the computer serving the document.
• The pathname to the document or a program to run on the server that will return the document.