padding is a property that allows the author to specify
how much space will be inserted between the element border
and the element content. Negative values are not
A paper prototype is a paper sketch of an interface with
just enough detail to make design decisions and usability
evaluations relating to the function and flow of the
interface, not the look.
Persistent Style Sheet
A persistent style sheet is a style sheet that is always
applied to the document. One example is the user agent's style
sheet: it is always applied, although you can override it with
your own styles.
PHP is an acronym for PHP hypertext Preprocessor. It is a
server side scripting language for creating dynamic web
pages. This means that it works within an
document to confer to it the capacity of generating content
on demand. You can convert your site into a web application,
not just a collection of static pages. A Web server processes
PHP script. After the server plays with the PHP code, it returns
plain old HTML back to the browser. This kind of interaction allows
for complex operations.
The word "pixel" is derived from "picture element". In
graphics, it refers to smallest resolvable rectangular area
of an image. It is how monitors divide the display screen
into thousands or millions of individual dots. In
a pixel is a relative unit of measure dependent on the
viewing device. Pixel units are relative to monitor resolution in
contrast to the percent or em units that are relative to a browser
setting. Percent and ems are considered best practice for
Pixels Per Inch (PPI)
Pixels Per Inch (PPI) is the resolution of an image file.
Web graphics and screenshots are made up of dots called
pixels. PPI is also the horizontal and/or vertical
density of an operating system's graphical display, from the
point of view of the operating system (and in turn, of the
applications and images running on it).
A plugin is a module (either hardware or software) that
adds a special feature to a larger system or program. For more
Plugins, PDF, PowerPoint, etc.
Pluralistic walkthroughs are when groups of users,
developers, and usability experts walk through a task
scenario. Group walkthroughs have the advantage of providing
a diverse range of skills and perspectives to bear on
usability problems. As with any inspection the more people
looking for problems, the higher the probability of finding
problems. Also, the interaction between the team during the
walkthrough helps to resolve usability issues faster.
Portable Document Format (PDF)
PDF is a file format developed by Adobe
Systems Inc., as a way to publish documents electronically,
with good formatting for printing, and document security
(documents are generally read only). Originally it was in an
image format. It was conceived as a way to make Adobe's
Postscript printer language portable, and it mostly developed
along the lines of press printing document production. Its
prevalence can be attributed to the ease with which one can
create PDF files. PDF has accessibility and usability
issues. One of the main problems with PDF concerns
accessibility issues associated with the document format, but
this is only part of the problem. Even when users have the
technology required to access information presented in this
format, there can be content elements which have not received
appropriate treatment to support accessibility such as using
structural formatting for headings, etc. or text equivalents
for images. Compared to
HTML, PDF is slow
and cumbersome. Many applications can save to
formats other than their native file format, such as
HTML, so this
option when available is preferable to PDF, even
when it needs to be cleaned up for the web. For more
Portable Network Graphics format (PNG)
PNG is an image format was developed as the successor to
the GIF format. It has a more efficient compression algorithm
Preferred Style Sheet
These style sheets are enabled by default. They are
"on" when the page is loaded. They can then be
disabled if the user selects an alternate style sheet. To make
a style sheet preferred, the rel attribute is set to "stylesheet"
and the style sheet is named with the title attribute.
Presentational markup directly describes the way content
should be displayed, rather than its structure or semantics.
It is markup used to control the visual appearance of a web
page. In contrast structural markup is
used to provide a logical meaning and structure to a
document. Presentation markup is meaningless outside of a
visual medium. The use of presentation markup is strongly
discouraged. It is generally considered best to separate
structural markup from presentation markup. In fact, if
you are in doubt as to whether a certain piece of markup is
structural or presentational, a good test is to ask, "how
might that be rendered in voice".
Primary navigation is the general menu choices that are
repeated on most (if not all) of the pages contained in the
site. It is sometimes called the main menu. Primary
navigation is sometimes referred to as global navigation or
functional navigation. Primary navigation bars provide
shortcuts to main sections on a website.
invented the phrase "print disabled" to describe
people who could not access print. It refers to a person
who cannot effectively read print because of a visual, physical,
perceptual, developmental, cognitive, or learning disability.
The Google Library Project Settlement defines "print
disabled" as a "User is unable to read standard
printed material due to blindness, visual disability, physical
limitations, organic dysfunction or dyslexia."
"Programmatic Determinable" means that a specific value can
be determined in a standard, machine or software readable
form. Assistive technology does not have to guess about it,
or use heuristics. It is authoritative, precise, and provides
unambiguous specificity. It allows software, including
assistive technology, to extract and present the information
in different modalities.
Progressive enhancement is a web design strategy, which is
the opposite of
graceful degradation. A basic markup document is created, geared towards the
lowest common denominator of browser software functionality,
and then the designer adds enhancements to the presentation
and behavior of the page, using modern technologies like
CSS a property
is named style attribute or parameter for a
markup element specified in a style sheet declaration, e.g.
color, background, font-family, padding etc., that is
assigned a certain value. Properties are always followed by a
colon to separate them from their value pair. A declaration
contains one or more properties the individual pieces of
style to be applied to the selected element.
A prototype is a partially completed mockup of your final
website. Prototyping allows you to test certain parts of the
final website, especially when it is incomplete. With many
sites, this model can be as simple as paper-and-pencil
drawings or as complex as actual working code. For more
In CSS, a pseudo-class is way of selecting certain parts
of a HTML document based in principle not on the HTML
document tree itself and its elements or on characteristics
like name, attributes or contents, but on other phantom
conditions like language encoding or the dynamic state of an
element. The original pseudo-class defined dynamic states of
an element that are entered and exited over time, or through
user intervention. CSS2 expanded on this concept to include
virtual conceptual document components or inferred portions
of the document tree e.g. first-child. Pseudo-classes operate
as if phantom classes were added to various elements.
In CSS, pseudo-elements are used to address sub-parts of
elements. They allow you to set style on a part of an
element's content beyond what is specified in the documents.
In other words they allow logical elements to be defined
which are not actually in the document element tree. Logical
elements allow implied semantic structure to be addressed in