The WDG's glossary of terms

Absolute URL: An absolute URL is an URL which completely and unambigously defines the location of a document or resource. It can be used out of context, but it will still point to the same file. If the meaning of the URL would change if it were taken out of context, it is called a relative URL.
Attribute: An attribute goes with a tag to provide some extra information, or to modify the meaning slightly. An attribute can have a value, but this is not necessary. The value should be put inside double quotes if it contains anything more than letters, digits, periods and hyphens.
Backbone: A major connection within the network of computers that make up the Internet.
Bandwidth: A very diminishing natural resource... bandwidth is a measure of the amount of data passing through a network at a given time. Things like huge images on web pages and needless questions posted to Usenet newsgroups waste bandwith which could be better utilized for transferring information.
Bit: A single piece of data. A bit has a numerical value of either "1" or "0".
Block-level element: A block-level element is a tag which is used to group a large section of text together to assign it a particular meaning, or to group a number of other elements together to form a unity. Block-level elements make up the document's structure.
Browser: Software that allows you, the client, to view World Wide Web resources.
Byte: A chunk of data made up of 8 bits.
Character-level element: A character-level element is used inside a block-level element to mark up a bit of text in a particular way. It should not be used outside block-level elements.
Container element: A container element is an HTML element which has an opening and closing tag, so it can contain data.
CyberSpace: A nickname for the collective systems known as the Internet.
Document type definition (DTD): An SGML document, which formally defines the relationship between elements, what attributes each entity has and which values these attributes may take. Used by validators and checkers to make sure your documents adheres to the standard.
Domain Name: A unique identifier which assigns a name to a specific IP address. Since IP addresses are merely strings of numbers, the Domain Name system was developed to facilitate ease of recognition and recall of site addresses.
Element: An element, often referred to as tag, is what HTML is constructed with. It has a name, perhaps one or more attributes and can be a container or empty.
Empty tag: A starting tag which does not have an ending tag. Because it doesn't end, it cannot enclose anything so it's always empty. Note that a tag which does have a closing tag, but does not contain anything is also empty, but such an empty tag may be ignored by a browser.
Entity: A special sequence of characters, representing another character. An entity starts with "&", ends with ";" and should contain the name or the number of the entity. If you use a number, put "#" in front of it. Check the section on the HTML character set for a list of entities and their numbers.
Extension: A tag or attribute introduced by a browser which is not part of the current HTML specification, and usually only supported by that browser. Other browsers should just ignore it.
FAQ: A list with Frequently Asked Questions and their answers. Usually accompanies a Web site or Usenet newsgroup to provide an introduction to the site or group, so you can easily locate necessary information while the regular users don't have to answer the same questions over and over again.
FTP: File Transfer Protocol is a method to transfer files from one location to another, either on local disks or via the Internet.
Finger: A protocol with which you can get information about a user on the Internet. It is generally only available for UNIX systems, although there are also clients for Macintosh and Windows.
Homepage: The central document on a World Wide Web site. This document usually directs clients to the information that can be found within the site.
HTML: Hyper Text Markup Language is the language of the World Wide Web. HTML is used to write documents on the World Wide Web, and to "glue" other resources together.
HTTP: Hyper Text Transfer Protocol, a protocol to transfer files similar to FTP, but with a built-in identification of the types of the file (the MIME type). Primarily used to transfer HTML documents.
Hypertext: A document that contains highlighted areas which when selected automatically transfer the client to a different location within the original document, or another document, image, movie or other resource.
IP: Internet Protocol, the most basic protocol to communicate on the Internet. An IP number is a numerical address consisting of four numbers seperated by periods. Each IP address uniquely identifies a certain computer on the Internet. The domain name is used to make using them easier.
ISP: Internet Service Providers provide access to the services offered by the Internet.
Newsgroup: Usenet Newsgroups, as they're formally called, started out separately from the Internet. Right now, most people read newsgroups via the Internet, although it is also popular in the BBS world. A newsgroup is devoted to a specific topic, which can usually be guessed by its name. They are generally unmoderated, and everyone is free to contribute.
Relative URL: An URL which is not complete, and must be expanded to an absolute URL before it can be used. The mechanism behind this expansion is discussed in more detail in my article on using relative URLs.
Resolution: A width x height measurement of computer monitor display capabilities in pixels. Some different types of displays are VGA or SVGA and different standard resolutions are 640x480, 800x600, and 1024x768.
Search Engine: A system dedicated to the search and retrieval of information for the purpose of cataloging the results. Usually based on an index of several HTML documents, so you can easily locate the document(s) you are looking for.
Server: A computer system which can be accessed from remote systems for the purpose of exchanging data.
T-1: A type of network connection which allows for data transfer rates up to 1.5 mega-bits per second.
T-3: A type of network connection which allows for data transfer rates up to 45 mega-bits per second.
Tag: This is the popular name for an HTML element, although there is a slight theoretical difference. Basically, a tag is an element in action. It starts with "<" and ends with ">". It can have attributes, but this is not necessary. The end of the element is signaled with the tag without its attributes, and with "/" as the first character. For example, the ending tag for <B> is </B>.
Text-level element: See character-level element.
URL: An Uniform Resource Locator is the standard way to express the location of a resource on the Internet. It is used most extensively on the Web. When you want to embed an URL in a document which does not support this directly, use the <URL:> convention. For example: <URL:http://www.htmlhelp.com/>.
Usenet: The collection of newsgroups.
Validator: A program or script which is used to check the validity of HTML markup, or to detect bad or deprecated elements. A validator helps to ensure that the document can be read and used by all browsers and search engines.
Virtual Server: To assign multiple domain names to one computer, it runs several virtual servers. This way, different domain names can be used without having to hook up a new computer for each of them.