Glossary of Internet Terms

Letter D

©2002 by Walt Howe
(last updated 22 October 2012)


 

Select the first character of the term you want to look up or use the Search link on the right.

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This Internet Glossary is growing. Terms and definitions are being added all the time. If you have comments, corrections, or suggested additions, please send them to Walt Howe using the form at the end of the Glossary. My thanks for the many suggestions that already have been included.


Web Developers! See how to link to terms in the glossary from your web page.

D

 

database
A collection of data records. On web databases, records may consist of web pages, or graphics, or audio files, or newspaper files, or books, or movies, or press releases, or almost anything from very general to very specific areas of interest. Records may or may not be further broken into fields. Database records are usually indexed and come with a search interface to find records of interest. See search engines.
datagram
In TCP/IP networks, datagram is a synonym for packet.
Delphi

  1. Delphi Forums. An Internet service and content provider. It was established in 1983 and was the first national provider to add Internet access in 1992. See Internet History
  2. An application development language from Inprise (formerly Borland).
  3. A method of forecasting future developments based on repeated surveys of experts with anonymous feedback of results in between rounds of questioning.
DHTML
See Dynamic HTML.
differentiated services
At present, all packets on the Internet are treated alike, regardless of their importance. If you want an important message to be delivered immediately or a streaming video signal to be distributed smoothly and without interruptions, there is no way to differentiate between immediate needs and routine transmissions which could be delayed for a long time without any problems. There are currently efforts under way to test and develop standards for differentiated services, where high priority data can be sent through or around clogged nodes ahead of low priority data. The high priority data transmission will cost more, of course. See ATM.
dither
To simulate a color that is not part of the current palette on-screen (or in print) by combining pixels of different colors close to each other. Viewed from a distance, it gives the effect of the color. Viewed closely, the dots are visible. Dithering can give a noisy appearance to a picture on-screen, but it often can be avoided by selecting non-dithering colors that are compatible with different browsers and platforms. See RGB and Creating Small, Fast-Loading Graphics for Web Pages for more help with this.
Dithered
color

Magnified
8 times
Digital Nervous System (DNS)
A term used by Bill Gates in frequent speeches in 1997 and 2000. Gates describes a future merging of PCs and communications in a wireless networked environment that makes it easy for people to navigate and share information. He speaks of a wireless pocket tablet ("a computer in every pocket") that enhances communications from many sources, aids in pattern recognition, and largely replaces telephone calls and paper messages and forms in business.
DjVu
Pronounced "deja vu". It is a compressed graphics format for showing scanned pages on the web. It does for scanned pages what PDF format does for electronically created documents. It requires a plug-in from AT&T. It uses a combination of compression formats that handles sharp-edged text one way and photographs and color blends another way, thus giving better compression than GIF, JPEG, or PNG can do. The server the document is placed on must be set for the MIME types x-djvu, djvu, and djv. For more information, see the AT&T DjVu FAQ.
Domain Name System (DNS)
Domain Name System. DNS servers are located at many strategic places on the nets to resolve the routing of e-mail and Internet connections. There are thirteen major, top-level DNS servers, which are updated daily, and these in turn feed the updated DNS information to smaller subordinate DNS servers, which hold more detailed information on their specific areas of coverage. No single DNS server has all the address information of the Internet, and successful routing may require routing through several levels of servers.

domain name
Domain name addresses, together with IP addresses, are the two forms of Internet addresses in common use. Domain name addresses all end with a correct top-level domain. The top-level domains may be any of these:

     

  • com
  • edu
  • gov
  • int
  • mil
  • net
  • org
  • a two-letter country code, such as us, uk, or mx. See the country code table.

The Internet Corporation for Assigned Names and Numbers (ICANN) announced a new series of top level domains available for registration with more to come. They are:

  • aero
  • asia
  • biz
  • cat
  • coop
  • info
  • jobs
  • mobi
  • museum
  • name
  • post
  • pro
  • tel
  • travel

A complete domain address adds one or more terms to the left of the top-level domain, separated by dots. The top-level domain at the right is the most general; each term to the left is more specific.

dOoDz
Pronounced "dudes." Immature scofflaws. See wareZ
DOS (See also DoS, which follows)
Acronym for Disk Operating System. Literally, the term refers that portion of an operating system that controls writing, storage, and retrieval of data from storage media, usually spinning disks of various types. In common usage, the term refers to MS DOS, the complete operating system developed by Microsoft for IBM-compatible personal computers in text (non-Windows) modes.
DoS (See also DOS, preceeding)
Acronym of Denial of Service, a form of assault on an Internet site which floods the site with packets requiring a response, thus slowing down or preventing normal access to the site.
dot-com
Nickname for the many commercial businesses that have registered names in the .com domain.
download
To transfer a file from another system to your own computer system via a modem over telephone or cable lines or a telnet connection using a transfer protocol like xmodem, ymodem, zmodem, or Kermit. Less precisely, it may also refer to a direct transfer from a server to your local terminal over a local area network or an FTP transfer from a remote system to your system. See upload.
DQYDJ
Chat slang shorthand for "Don't quit your day job!"
DSL
Acronym for Digital Subscriber Line or Digital Subscriber Loop, often referred to as xDSL. It refers to several new digital technologies for fast two-way data connections over ordinary telephone lines. Rockwell announced a new Consumer DSL or CDSL technology in October 1997, which offers speeds up to 1MBps. US West introduced RADSL. The other technologies offer speeds up to 8 times as fast as that, but require more complicated installation. Rolloout has been slow, but it is spreading rapidly now. See ADSL.
DTD
Acronym for Document Type Definition or optionally Document Type Declaration, used in SGML and XML markup languages to specify the set of rules or grammar processed in a particular language. HTML versions each have their own DTD, for example.
Dublin Core
A proposed set of standard descriptive metadata elements used with web resources to aid in resource discovery. The elements are intended as a starting point for resource description. The elements are optional, and are intended to be extensible to richer descriptive elements when needed. The 15 elements are:

     

  • title
  • author/creator
  • subject/keywords
  • description
  • publisher
  • other contributor
  • date
  • resource type
  • format
  • resource identifier
  • source
  • language
  • relation
  • coverage
  • rights management

See the Dublin Core Homepage for further information.

Dynamic HTML (DHTML)
A more powerful model for HTML that allows absolute control of positioning of elements on a page and more powerful control of events. It is supported by MSIE 4.0 and partially by Netscape 4.0.

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For Web Developers: How to Link to the glossary terms.
You can link to any term in this glossary with a link in this form:

http://www.walthowe.com/glossary/*.html#term

Replace the asterisk in *.html with the first letter of the term you are linking to. Terms with more than one word will generally use an underline to link the words.