Database Website
A website connected to a database causing web page content to be called up or retrieved from the database and then displayed to the viewer.

Dead link
A link which points to another web page which no longer exists. Usually returns “Page Not Found” message.

Dedicated Server
A server limited to serving one website or a small collection of websites owned by a single person. Dedicated servers tend to be more reliable than shared (or virtual) servers.

Del.icio.us
A popular social bookmarking website.

Description
Directories and search engines provide a short description near each listing which aims to add context to the title.

Digg
A social news site where users vote on which stories get the most exposure and become the most popular.

Directory 
Human edited website where editors sort submitted websites into categories. DMOZ and Yahoo are examples. Editors may edit descriptions that are submitted to them.

DNS
(Domain Name Server or Domain Name System)
A naming mechanism used to help resolve a domain name / host name to a specific TCP/IP Address.

Doorway Page (bridge page" or a "gateway page”)
A web page that is designed specifically to attract traffic from a search engine. A doorway page redirects users (but not spiders) to another site. Doorway pages are considered to be search engine spam by the search engines.

Duplicate Content
Content which is similar or identical to that found on another domain or webpage can cause mistrust from visitors and search. The more original content is the better.