In
CSS
half-leading is the leading split in half and applied
equally to the top and bottom edges of the element's
content-area. The difference between font-size and
line-height, is applied equally above and below the
content-area for each element.
Haptic
Haptic technology provides a user tactile feedback, for instance
vibration or motion.
HCI
HCI stands for "Human Computer Interaction." It is the
study of how people relate to electronic tools and
interfaces.
Head Pointer
A device attached to the user's head, that allows a user
to move the pointer on the screen, (usually moved by the
mouse, a pointing device, the arrow keys, or with the
movement of their head). It is useful for people who have
limited mobility.
Headings
In HTML there are 6 levels of headings, h1 through to
h6. To maintain the logical structure of a document,
headings should follow a logical progression. Headings of
level 3 shouldn't follow directly from headings of level 1,
only from headings of level 2. You should always try to
maintain a distinction between appearance and logic. Simply
because an element is a heading of level 2 does not mean that
it will be rendered larger and bolder than regular text in
the document. Style sheets allow a web designer to very
easily apply any styling to a heading. Keep in mind too, that
there are browsers which don't display information in a
visual way, relying on text to speech conversion, or Braille
conversion. For maximum accessibility, structural elements
such as headings should be used correctly, and appropriately.
Also
consult structure.
Hearing Disability
The condition of a person who experiences partial or
total loss of hearing.
Heuristic (Expert) Evaluation
Heuristic evaluation is where a group of usability
experts scrutinize a website and evaluate each element of the
site against a list of commonly accepted principles or rules
of thumb. They apply their training and experience to conduct
independent evaluations. Research shows that such evaluations
can identify a majority of the usability problems, with the
problem-identification percentage increasing as evaluators
are added. The major drawback of heuristic evaluation is that
evaluators, regardless of their skill and experience, remain
surrogate users (expert evaluators who emulate users) and not
necessarily typical users of the product. For more
information consult
Heuristic Evaluation.
Hexadecimal
Hexadecimal numbers are used in HTML and CSS, and other
computing applications, to represent colors. The bytes
represent the red, green and blue components of the color.
One byte represents a number in the range 00 to FF (in
hexadecimal notation), or 0 to 255 in decimal notation.
Concatenating three bytes in hexadecimal notation forms the
hex triplet. The system uses numbers from 0 to 9 and
letters from a to f in any combination of six (and starting
with an octothorpe) to represent the correlating red, green,
and blue colors (#RRGGBB). e.g. #FFFFFF = 255, 255, 255 =
white.
Hierarchy
Hierarchy is a top down organizational structure.
Horizontal Scrolling
Horizontal scrolling is scrolling sideways within a web
browser's window. When a site has content that is wider than
the browser window, users must scroll horizontally to see it.
Horizontal scrolling should be avoided if possible. It's
awkward to do and users hate it.
Hue
Hue is the name of a distinct color of the spectrum (e.g.
red, green, yellow, orange, blue). It is the particular
wavelength frequency.
HyperText Markup Language (HTML)
The markup language that is used on most of the World
Wide Web to create web pages. The standards for
HTML
are controlled by the
W3C.
