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.
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 cannot 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.
Deprecated
In HTML 4 a deprecated element or attribute was
one that has been outdated by newer constructs. The
term does not exist in HTML5.
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
white space. A descendant selector of the form "A B" matches
when an element B is an arbitrary descendant of some ancestor
element A.
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.
Digital Divide
The gap that exists between those who have access to
electronic and information technology, and those who do
not.
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.
Doctype
Document Type Definition (DTD) is a file that
defines how applications interpret a
document.
Doctype Switching
A mechanism that was used prior to HTML5 by which browsers
examine the DOCTYPE (or lack thereof) contained in a document,
and picked a rendering mode to match it.
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 is 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. A dot per inch (number of pixels) also measures
resolution on output devices such as monitors and printers.
Dividing the resolution of the device by the physical
dimensions of its imaging region arrives at the horizontal
and/or vertical density of the output device.
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.
