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.
DeCSS
DeCSS is a software program that allows decryption of a CSS-encrypted movie and copying of the files to a hard disc (CSS stands for content scrambling system, and it’s used to protect the content of a DVD disc.) The DeCSS utility made online trading of DVD movies possible, although the interactive elements and outstanding audio/visual quality of DVD are compromised in the process. The program caused a major controversy when released in late 1999, with the movie industry fearing a massive wave of piracy was about to begin.
Degrade
How a Web page "degrades" refers to how it will be displayed by older or less popular browsers. The hope is that the Web page will "degrade gracefully," meaning the images and text will be displayed in roughly the same way across a variety of browsers and platforms. If a designer relies heavily on JavaScript, for example, then the site will not work correctly on older browsers and thus not degrade gracefully. This problem of browsers interpreting Web pages differently is one reason why protocol is so important. If everyone agreed on one protocol for using HTML, then it would be considerably easier to control how Web pages degrad.
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.
Device Independent
A program or application that will work on any peripheral devices within a certain protocol is considered device independent. Dialing a telephone number is a simple example of a device-independent action -- all telephones operate under the same protocol, so no matter what brand of telephone you use, you can always phone home. Device independence ensures that all Internet-enabled devices -- everything from a Sony Playstation to a Web-surfing clock radio -- will be able to communicate with each other in the future.
DHCP
The dynamic host configuration protocol is an addressing protocol for TCP/IP networks. IP addresses are leased to individual computers on the network from a DHCP server. DHCP allows users to move to different locations on a network without having to bother a network administrator (and they hate being bothered) to manually assign a new IP address. DHCP is useful in homes with several computers sharing a single high-speed Internet connection.
Digerati
The digital version of literati, it is a reference to a vague cloud of people seen to be knowledgeable, hip, or otherwise in-the-know in regards to the digital revolution.
Direct Response
On the Web, direct response usually refers to a clickthrough on an ad banner. Many advertisers will audit the effectiveness of a campaign based on the number or percentage of direct responses. While this can lead to the hard-bargain, cost-per-click deals that almost entirely ignore the branding value of Web advertising, evaluating response is often the best way to an honest audit of the product, advertising message, and ad placement.
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)
DNS
The domain name system (DNS) is an Internet service that translates domain names (like hotwired.com) into IP addresses (like 204.160.88.11). We use domain names because people can remember words better than numbers, but Web servers still need the IP numbers to access the page. Every time you use a domain name, a DNS server must translate the name into the corresponding IP address.
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.
DOM
The document object model (DOM) is the proposed specification for how objects on a Web page are represented. Of course, Microsoft and Netscape each have their own versions of the DOM and have submitted them to the World Wide Web Consortium (W3C) to decide on a standard. A DOM defines each object on a Web page (images, text, scripts, links, etc.) and also defines what attributes are associated with these objects and how they can be manipulated. The fact that Netscape Navigator and Microsoft Internet Explorer use different DOMs is one reason why each browser's implementation of dHTML is different.
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)
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.
DPI
Dots per inch measures the resolution of images on a screen or printed page. Most laser printers use 600 DPI - 600 across and 600 down. The more dots, the better the resolution.
DSL
A digital subscriber line, or DSL, is a communications technology that allows data to travel at very high speeds over standard telephone wire without interrupting normal telephone service. The primary market for DSL is the home office since the technology makes it easy for residential homes to receive high-speed Internet access at a reasonable price. DSL speeds, on the average, run at about 600kbps for downstream and 128kbps for upstream.
DSL
(Digital Subscriber Line) -- A method for moving data over regular phone lines. A DSL circuit is much faster than a regular phone connection, and the wires coming into the subscriber’s premises are the same (copper) wires used for regular phone service. A DSL circuit must be configured to connect two specific locations, similar to a leased line.
A commonly discussed configuration of DSL allows downloads at speeds of up to 1.544 megabits (not megabytes) per second, and uploads at speeds of 128 kilobits per second. This arrangement is called ADSL: “Asymmetric” Digital Subscriber Line.
Another common configuration is symmetrical: 384 Kilobits per second in both directions.
In theory ADSL allows download speeds of up to 9 megabits per second and upload speeds of up to 640 kilobits per second.
DSL is now a popular alternative to Leased Lines and ISDN, being faster than ISDN and less costly than traditional Leased Lines.
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.
Duotone
Duotones are images that only display in two colors. Like most visual techniques on the Web, duotones come from the world of print. In print, the more colors you use, the slower the production time and the higher the cost, so duotones were often an economical alternative. Duotones can also improve efficiency on the Web by enabling the creation of cool-looking images with small file sizes. Duotones are made by first creating a grayscale image and then overlaying it with a different specified color. Many of the head shot pictures of Webmonkey writers are duotone images, for example.
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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