Data Table

A table that is used to present data in a tabular or spreadsheet format. This contrasts with a layout table that uses the same construct for a different purpose. In a data table contents of a cells are related to cell contents in adjacent cells.

Deafness

A condition of a person who can not hear at all.

Declaration

In CSS, a declaration is part of a statement or rule. It is the portion of the statement which suggests to a browser how selected elements should be rendered. A declaration contains one or more properties the individual pieces of style to be applied to the selected element. It consists of pair of property and value parameters.

Deep Linking

Deep links are links that go directly to an inner page of a website rather than the homepage. It enables direct linking to highly appropriate and specific content.

Degrade Gracefully

An element on a web page is said to 'degrade gracefully' if ignoring it does not prevent content on the page from being obtainable and functional.

Deliverable

In project management, deliverables are the output of what you are doing. It refers to the defined end products, results, or services of a project.

Device Independence

For Web content to be device independent, it should be possible for a user to obtain a functional presentation associated with its Web page identifier via any access mechanism.

Deprecated

A deprecated element or attribute is one that has been outdated by newer constructs. Deprecated elements may become obsolete in future versions of HTML . Authors should avoid using deprecated elements and attributes. The W3C recommends in Checkpoint 11.2 that deprecated elements and attributes not be used, mostly because they force styles and design upon a user instead of using style sheets that allow a user to override the default style. A listing of deprecated elements and attributes can be found at: http://www.w3.org/TR/REC-html40/index/elements.html and http://www.w3.org/TR/REC-html40/index/attributes.html.

Descendant Selectors

At times, authors may want selectors in CSS to match an element that is the descendant of another element in the document tree (e.g., "Match those EM elements that are contained by an H1 element"). Descendant selectors express such a relationship in a pattern. A descendant selector is made up of two or more selectors separated by whitespace. A descendant selector of the form "A B" matches when an element B is an arbitrary descendant of some ancestor element A.

Disability

According to the Americans with Disabilities Act, " The term means, with respect to an individual (A) a physical or mental impairment that substantially limits one or more of the major life activities of such individual; (B) a record of such an impairment; or (C) being regarded as having such an impairment."

Disability Discrimination Act (DDA)

A name shared by two laws passed in Australia (1992) and the United Kingdom (1995). They both prohibit discrimination against people with disabilities. The goal is that a functional presentation should be possible via any access mechanism. The method of presentation may vary according to the different access mechanisms, but the possibility of a functional presentation should always exist.

Dithering

In computer graphics, dithering is a method of creating additional colors and shades from an existing palette by interspersing pixels of different color in computer graphics to create additional colors and shades from an existing palette by interspersing pixels of different colors

Digital Divide

The gap that exists between those who have access to Electronic and Information Technology, and those who do not.

D link

A "description link" that takes the form of a capital D and is located near an image. It is linked to a separate page containing a description of the image. This enables blind users or users of text browsers to understand the content of an image without actually seeing it.

Doctype, Document Type Definition (DTD)

A file that defines how applications interpreting a document should present the content. It is used in HTML , XML , and other Markup languages. A DOCTYPE is a means of specifying what syntax a web page uses. Include a document type declaration at the beginning of a document that refers to a published DTD (e.g., the strict HTML 4.0 DTD). The document type declaration should be appropriate to the markup language you are using. It should appear at the very beginning of an HTML document in order to identify the content of the document as conforming to a particular HTML DTD specification.

Doctype Switching

Switching is the mechanism by which browsers examine the DOCTYPE (or lack thereof) contained in a document, and picks a rendering mode to match it. Typically, older or malformed DOCTYPEs cause browsers to enter "quirks" mode, which emulates historical authoring practices built around the flaws found in older browsers. Newer DOCTYPEs will trigger "strict" mode, where they attempt to hew as closely as possible to the abbr title="World Wide Web Consortium">W3C recommendations in order to deliver a more consistent cross-browser experience. This lets authors decide which mode to use, a decision which is generally fueled by their target audience. The browser doesn't actually use the DOCTYPE to validate the content -- it only uses this string to toggle specific behavior of the renderer.

Document Tree

The tree of elements encoded in the source document. Each element in this tree has exactly one parent, with the exception of the root element, which has none.

Dots Per Inch (DPI)

Dots Per Inch is a term that also refers to printing and the amount of ink that actually is placed upon the print medium. Dots Per Inch is a property of a print graphic and determines how it prints - its size and quality. Color printing isn't done in continuous color, it's done with individual dots of Cyan, Magenta, Yellow and Black (CMYK), lots of them, giving an impression of continuity. These are the dots in dpi. Dots per inch (number of pixels) also measures resolution on output devices such as monitors and printers. The horizontal and/or vertical density of the output device, is arrived at by dividing the resolution of the device by the physical dimensions of its imaging region. A Mac monitor is typically 72 dpi. A PC monitor is typically 96 dpi. Most laser printers have output resolution of 300-600 dpi and produce good results with images which have image resolution of 72-150 ppi.

Dyslexia

A language based learning disability that is often characterized by difficulties with understanding written language, and being more attuned to a graphical or object based learning style.