Dead Link: Dead link means html link destination page no longer exit. One of the major problems for search engines these dead links, so search engines are spidering the pages again and again routinely to try find "dead links".

Deep Linking: In website content buried deep with the link. Two or more directories deep in a websites so it is referred as "deep".

Defaults: Defaults are filled with PSA ads, or blanks and etc, because when advertiser doesn't have enough advertisements to fill the websites inventory.

Direct Hit: A system which monitors users' selections from search engine results, counting clicked result on which are more times, and how long visitors spend at that site, so as to improve relevancy.

Directory: Directory is a website that contains various topics.

DNS Lookup: Process of converting an IP address to its domain names. Mostly used by webmaster for analyze server log files.

Dogpile: Dogpile is a met search engine that fetches results from Google, yahoo, Windows Live Search and etc.

Domain: Domain is a term used to describe top level domains as .com, .net, .org, middle level domain as for.com and plays an important role in determining sites rankings.

Domain Name Registration: The Act of registrar approved registering the domain name and process is overseen by ICANN.

Doorway Domain: A domain designed for redirecting the traffic to a main website which is located in another domain.

Doorway Page: Doorway page means a page which is designed as welcome page of a website, these doorway pages a specially created for high rank websites, search engines and also referred as welcome mat page or gate way page.

Download: When information is send from any system in network is copied or extracted that files is called Downloading.

Dynamic Content: The content that just viewed by user. In this content is updated automatically often from the database.

Dynamic IP Address: An IP Address that Changes every time when you connect the internet connections.