Dead Link - See Broken Link.
Deep Linking - Linking to a page that is one or more levels removed from the home directory. Deep linking is often desirable to build PageRank to a specific page on a website.
Example:
http://www.yoursite.com/tutorials/diy-seo.html
Description - A short sentence or paragraph that describes a web page's content, usually used as part of a link to describe the page being linked to. See also link anchor text.
Description Meta Tag - A meta tag that describes the content of the web page in which it is found. Used by some search engines for keyword density purposes. Also, some SE's will use the description meta tag for the description provided to a user when the page is returned in a listing of search results. It is recommended that you use a couple of your targeted keywords in the description meta tag.
Example:
<META NAME="Description" CONTENT="This sentence
describes the content on this page.">
Directory - A categorized list of websites that is maintained by human editors instead of crawlers. Yahoo.com is the most widely recognized directory on the web, but there are literally thousands of others.
Domain - The human-friendly "address, or URL" of a website. When a user types a URL into a web browser, a dedicated computer somewhere on the web known as a Domain Name Server, or DNS translates the URL into a discrete IP address which is then used to find the actual website being requested.
In the URL http://www.rlrouse.com, rlrouse.com is the domain.
Domain Name Servers (DNS) - These are special computers that translate human-friendly URLs into computer-friendly IP addresses. This process takes place every time a user requests a page from a website.
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.
Doorway Page - A page that is usually optimized for a particular search engine and search term. Multiple doorway pages are often used to help ensure that the same basic content is ranked well on several different search engines. The use of doorway pages for this purpose is frowned upon by most larger search engines, including Google.
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 their crawlers are active on 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 (dynamic pages) - Web pages that are often generated from database information based upon queries initiated by users. Dynamic pages often include the ? character in the URL.
The URLs of dynamic pages often use these extensions: .asp, .cgm, or .cgi. Most search engines don't index dynamic content very well (or at all). Google has recently been doing a better job at indexing them however.
Dynamic IP Address - An IP address that changes every time a computer logs on to the internet. See also Static IP Address.