D2D - Abbreviation for Distributor to Distributor.

DA - 2 Letter Language Code for Danish

Dangling Link - This term is applied to a web page with no links to any other pages. Also known as an Orphan Page.

Data Transfer - The total amount of outbound traffic from a website, typically measured in gigabytes (Gb).

Database - A method of storing data into tables.

DC - Abbreviation for Data Center

DC - Abbreviation for Dublin Core

DCMES - Abbreviation for Dublin Core Metadata Element Set

DCMI - Abbreviation for Dublin Core Metadata Initiative

DDL - Abbreviation for Data Definition Language

DDoS - Abbreviation for Distributed Denial of Service (see also: DDoS Attack)

DE - 2 Letter Language Code for German

Dead Link - A hyperlink pointing to a non-existent URL. A hyperlink which no longer exists.

Dedicated Hosting - Hosting option whereby the host provides and is responsbile for the equipment, dedicating an entire server to the client's websites.

Dedicated IP - An IP address dedicated to a single website.

Deep Crawl - Once a month, Googlebot crawl all of the links it has listed in it's database on your site. This is known as the Deep Crawl.

Deep Link - A link on a website that is not reachable from the home page.

Deep Web - see invisible Web

Delisting - When pages are removed from a search engines index. This may happen because they have been banned, or just deemed out-of-date or irrelevant, or for unethical practices, or for other reasons, such as an accidental glitch on the search engine's part.

Deliverable - In a contract, these are the expected results of the services provided.

DEM - 3 Letter Currency Code for Germany Deutsche Marks

Description Meta Tag - A HTML tag used by Web page authors to provide a description for search engine listings. A description tag usually looks like: <Meta name="description" content="We are doing blah-blah-blah"> Ideally, the description tag should be around 170 characters including spaces. Depending on the engine, additional characters over 170 may be truncated. The description is visible on the SERP with engines that support this tag some search engines, like Google; use a copy snippet for the description.

DH - Abbreviation for Direct Hit

DHTML - Abbreviation for Dynamic Hypertext Markup Language (see also: HTM, HTML, XHTML, XML)

Directories - A compiled lists of sites, categorized and organized by topic. Each directory listing contains short, descriptive information about the site. Usually human edited, a directory contains sites that are sorted by categories. They often involve an editorial review by a human editor who will visit your Web site after you submit to the directory. With directories, you dont have to worry about meta tags or search engine optimization techniques. Instead, you submit your Web site thru an online submission form which usually asks you to write the title of your Web site, normally your Web site name and a description of your Web site which describes the type of business, services provided or products offered, etc. after which an editor will visit your Web site. Yahoo and Open Directory are human based search directories. Strong directory listings are an excellent way your company can increase its link popularity and its Google PageRank.

Disintermediation - The elimination of intermediaries in the supply chain, also referred to as "cutting out the middlemen"

Disk Space - The amount of hard drive space on the server that is available to your websites.

DKK - 3 Letter Currency Code for Denmark Kroner

DMCA - Abbreviation for Digital Millennium Copyright Act. A declaration that protects digital works found online.

DML - Abbreviation for Data Manipulation Language

DMOZ - Abbreviation for Directory Mozilla also known as the Open Directory Project, as today "World's Largest Human Edited Directory." This directory employs stringent entrance standards for listing. It is very difficult (if not impossible) to obtain a place in this directory, although all together the most important directory for ranking highly in Google searches results. Read the DMOZ guidelines for inclusion here. (see also: ODP)

DNS - Abbreviation for Domain Name System. A protocol that lets computers recognize each other through an IP Address, whereas the human sees a website URL. A distributed directory used to translate between IP addresses and domain names.

DOC - Abbreviation for Word Processing Document also file extension filename.doc

Dogpile - The metasearch engine

DOM - Abbreviation for Document Object Model

Domain Name - The virtual address or URL of a particular Web site, it is the text name corresponding to the numeric IP address of a computer on the Internet, a name for an IP address that may have various suffixes, such as .com, .net, .edu, or .org. This is what people will type when they want to visit your site.

Domain Parking - Providing a nameserver for domains that do have their own hosting yet.

Domain Registration - Where people buy domain names

Dooced - Getting fired for negative blogging about the company you work for.

Doorway Domain - A domain used specifically to rank well in search engines for particular keywords, serving as an entry point through which visitors pass to the main domain.

Doorway Page - A low- or no-content page created especially with the purpose of ranking well on a search engine, usually very keyword heavy designed to draw in Internet traffic from search engines, and then direct this traffic to another website. Doorway pages rarely are written for human visitors. Most search engines frown on this SEO marketing practice. Usually dynamic pages are provided with a doorway page serving as an entry point through which visitors pass to the main content. Several search engines have guidelines against doorway pages, though they are more commonly allowed in through paid inclusion programs. Also referred to as bridge pages, gateway pages and jump pages, among other names. Using doorway pages is a violation of the Terms Of Service of most search engines and could be grounds for banning. (see also: Gateway Page)

DOS - Abbreviation for Disk Operating System

DRPs - Abbreviation for Directory Results Pages

DTC - Abbreviation for Direct Traffic Center (Overture/Yahoo! Search Marketing)

DTD - Abbreviation for Document Type Definition

DVD - Abbreviation for Digital Versatile Disk

Dynamic Content - Web page content that changes or is changed automatically based on database content or user information. You can usually spot dynamic sites when the URL ends with .asp, .cfm, .cgi or .shtml, but it's also possible to serve dynamic content with standard static pages (.htm or .html). Many search engines index dynamic content, but some don't if there's a "?" character in the URL.

Dynamic Page - Generally the website is Database Driven

Dynamic Site - A site that uses a database to store it's content and is delivered based on the variable passed to the page.