SEO Glossary - Letter D
Data Binding
As a computer science term, data binding is the substitution of a real value in a program after it has been compiled. For example, during compilation a compiler can assign symbolic addresses to certain variables or instructions. When the program is bound, or linked, the binder replaces the symbolic addresses with real machine addresses. The moment at which binding occurs is called "bind time" or "link time." In dHTML, data binding allows the client to look into a database and retrieve the content. This data can be automatically displayed in your table using the HTML data binding extensions, or you can manipulate the data with a script. Currently, dHTML data binding is only supported by Microsoft Internet Explorer.
Data Type
JavaScript's ability to distinguish data types is similar to a human's ability look at a number and know that it's a batting average or a percentage or a price tag. We use signs like % and $ to connote these sort of data types. In JavaScript, programs can manipulate data types according to how each type is expressed. These data types include integer, string, Boolean, functions, and objects.
datagram
A formatted set of electronic data used in communication between computer systems. Datagrams consist of two parts: the data proper (which may be part of a longer message), and the header (which indicates the source, the destination, and the type of data).
DDN
Defense Data Network) A segment of the Internet that links to US military bases and contractors around the world. Used for unsecured communications.
DECnet
A set of proprietary networking protocols utilized (instead of TCP/IP) by Digital Equipment Corporation's operating systems. These protocols are not compatible with the Internet.
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.
Demographics
Demographics are the DNA of marketing: age, sex, income, profession, marital status, location, and so on. Advertisers rely on demographics to help decide which sites are most likely to help them reach their specific audience. Knowing your audience demographic not only helps you sell ads, it also lets you know who your users are and what they want. To figure out your own site's demographics, download a copy of SurveySolutions, cobble together a survey, and post it on your site.
Directory
A categorized list of websites that is maintained by human editors instead of crawlers.
directory
An organized unit for file storage on a computer system. Also a listing of files residing within such a unit.
directory service
A service on a network that relays information about sites, computers, resources, or users in the area.
DLL
(Dynamic Load Library)
DOD
(Department of Defense) The branch of government whose Advanced Research Projects Agency (ARPAnet) began the creation of the Internet.
DOM
(Document Object Model) A platform and language neutral interface that allows programs and scripts to dynamically access and update the content, structure, and style of documents.
Domain Name
The unique name that identifies an Internet site. Domain Names always have 2 or more parts, separated by dots. The part on the left is the most specific, and the part on the right is the most general. A given machine may have more than one Domain Name but a given Domain Name points to only one machine. For example, the domain names:
matisse.net
mail.matisse.net
workshop.matisse.net
can all refer to the same machine, but each domain name can refer to no more than one machine.
Usually, all of the machines on a given Network will have the same thing as the right-hand portion of their Domain Names (matisse.net in the examples above). It is also possible for a Domain Name to exist but not be connected to an actual machine. This is often done so that a group or business can have an Internet e-mail address without having to establish a real Internet site. In these cases, some real Internet machine must handle the mail on behalf of the listed Domain Name.
Domain Name
The highest level name of the web site. For example, The domain name for USA Today Online is usatoday. If you type usatoday in the location area on your browser, you will be connected directly to USA Today Online. A site does not have to have its own domain name. I use geocities to host my web site and thus their domain name is included in my Internet address: http://www.geocities.com/FashionAvenue
Domain Name
The text name corresponding to the numeric IP address of a computer on the Internet (i.e., www.webtrends.com).
Domain Name System
DNS) The unique name of a collection of computers connected to networks such as the Internet. A general-purpose, replicated, distributed data query service for looking up host IP addresses based on host names. The DNS is hierarchical, consisting of domains, subdomains, sites, and hosts. Unique names are formed from smallest to largest, and are of the form user@host.site.subdomain.domain, where host and site are often optional. On the Internet, domain names typically end with a suffix denoting the type of site:
.com (commercial)
.edu (educational)
.net (network operations)
.gov (US government)
.mil (US military)
.org (organization)
.us (United States)
.ca (Canada)
.uk (United Kingdom)
.au (Australia)
.cz (Czech Republic)
.xx (where xx refers to another country's two-letter abbreviation)
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.
Download
The transfer of information from the Internet to your computer. Every time you instruct your computer system to retrieve your mail, you are downloading your mail to your computer. You may also download programs to your computer. However, be careful about downloading files or programs from a site in which you are not familiar. You could download a virus and never know it until it's too late.
DSS
(Digital Signature Standard)
dumb terminal
A terminal that doesn't contain an internal microprocessor. It responds to simple control codes, and usually displays only characters and numerals.
Duplicate Content
Multiples of separate web pages containing the same content are said to contain duplicate content.
dynamic HTML
(or DHTML) Instructions written in HTML that enable Web pages to react to user input and produce content that changes each time it is viewed. With dynamic HTML coding, Web pages are created "on the fly", as the information is delivered to your desktop. There are many technologies for producing dynamic HTML, including CGI scripts, Server-Side Includes (SSI), cookies, Java, JavaScript, Cold Fusion and ActiveX.
Dynamic SQL
see SQL) This feature modifies queries based on user data, environment variables, and previously returned query results. Dynamic SQL can also increase processing efficiency by executing multiple queries and sending them to multiple databases from a single browser request.
dynamic Web page
Web pages that respond to users' requests and gather information from them. Oftentimes, they have built-in links to a relational database, from which they extract data based on input from the user (using dynamic SQL). Dynamic Web pages contain very little actual text. Instead, they pull needed information from other applications. Dynamic Web pages communicate with databases to extract employee directory information, spreadsheets to display accounting figures, client-server database management systems to interact with order processing applications, and more. Because a database already exists, why re-create it for Web page publications?
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