DBMS (Database Management System) - A collection of programs that is used to store, modify, and extract information from a database.

Dead Link - A link that produces a 404 error, page not found.

Deep Linking - A link to a Web page other than your index page.

Description - Descriptive text summarizing a Web page and displayed with the page title and URL when the page appears as the result of a user query on a search engine or directory. Some search engines use the description in the description meta tag, others generate their own description from text on the page. Directories often use text provided at registration.

Description tags - A meta tag that allows the author to control the text of the summary displayed when the page appears in search engine results. Some search engines respond to this information, others ignore it.

DHTML (Dynamic HTML) - The next generation of HTML, the language that describes how text and images are displayed on a Web page. Dynamic HTML, developed by Netscape and the World Wide Web Consortium (W3C), is based entirely on industry-standard HTML and Java. New features in Dynamic HTML, such as absolute positioning and layers, give Web designers and developers much greater control over the look and feel of Web pages.

Dialup - A temporary connection between machines established with modems over a standard phone line.

Digital Signature - A digital code that uniquely identifies the sender and which is usually attached to an electronically transmitted document.

Director - A Macromedia product used in the production of interactive applications such as games. Director files are compressed and saved as Shockwave files.

Directory - A Web site that list other Web sites in their various categories.

DNS (Domain Name Service) - The Internet's distributed database system used to map names with the appropriate IP address. The DNS is a general-purpose distributed, replicated, data query service. The principal use is the lookup of host IP addresses based on host names. The style of host names now used in the Internet is called "domain name", because they are the style of names used to look up anything in the DNS. Some important domains are .COM (commercial), .NET (network), .EDU (educational), .GOV (government) and .MIL (military). Most countries also have a domain. For example, .US (United States), .UK (United Kingdom) and .AU (Australia).

DNS Propagation - Every time a new domain name is registered (or an existing one is transferred to a new DNS), the information about the domain and the DNS that hosts it must make its way around the entire Internet. This process usually takes around 24 hours, during which time the domain will be inaccessible to users.

Domain - The name associated with the numeric Internet Protocol (IP) address of a site on the Internet. Most of the domains that we will frequent are (dot) .com, .org, .edu and .gov (i.e. www.sitename.com)

Doorway Page - A Web page submitted to individual search engine spiders to meet specific relevancy algorithms. The doorway page presents information to the spider while obscuring it from human viewers. The purpose of doorway pages is to present the spider with the format it needs for optimum rankings while presenting a more appropriate version to human viewers. Also known as gateway pages, bridge pages, entry pages, portals or portal pages.

Download - Transferring or copying files from one computer to your computer over the Internet or any other communications link.

DPI (Dots Per Inch) - The spatial resolution of a graphics image, how many dots per inch in a graphic image determine the quality of output. A high-end printer can produce 600 1200+ DPI while a computer monitor is only 72 DPI.

Dreamweaver - A Macromedia Web-authoring product. Very popular, offering some very advanced capabilities such as automated JavaScript, simplified CSS programming and DHTML.

DSL (Digital Subscriber Line or Digital Subscriber Loop) - Often referred to as xDSL. It refers to several new digital technologies for fast two-way data connections over ordinary telephone lines.

Duplicate Content - Two or more separate Web pages that contain substantially the same content are said to contain duplicate content. Google and other top search engines have set up filters to detect duplicate content when they crawl the Web. When pages containing duplicate content are detected, they are often assessed a duplicate content penalty which means a lowering of the page's ranking from what it would have received naturally.

Dynamic Content - Information on Web pages which changes or is changed automatically, e.g. based on database content or user information. Sometimes it's possible to spot that this technique is being used, e.g. if the URL ends with .asp, .cfm, or .aspx. It is possible to serve dynamic content using standard (normally static) .htm or .html type pages, though. Search engines will currently index dynamic content in a similar fashion to static content, although they will not usually index URLs which contain the '?' character.

Dynamic IP Address - An IP address that changes each time you log onto the Internet. Most dial-up connections.

Dynamic Web Pages - As opposed to static Web pages. A fusion of HTML code and database information used to create Web pages. For example, a user can request information through a form to access information stored in a database, which will then be created on the fly and presented.