What Accessibility Means
Providing accessibility means removing barriers that prevent people with
disabilities from participating in substantial life activities, including
the use of services, products, and information. We see and use a multitude
of access-related technologies in everyday life, many of which we may not
recognize as disability related when we encounter them. The bell that chimes
when an elevator is about to arrive, for example, was designed with blind
people in mind. The curb cut ramps common on street corners in the United
States were introduced for wheelchair users. Accessibility is by definition
a category of usability: software that is not accessible to a particular
user is not usable by that person. As with any usability measure, accessibility
is necessarily defined relative to user task requirements and needs. For
example, a telephone booth is accessible (e.g., usable) to a blind person,
but may not be accessible to a person using a wheelchair. Graphical user
interfaces are not very accessible to blind users, but relatively accessible
to deaf users.
Assistive access means that system infrastructure allows add-on assistive
software to transparently provide specialized input and output capabilities.
For example, screen readers allow blind users to navigate through applications,
determine the state of controls, and read text via text to speech conversion.
On-screen keyboards replace physical keyboards, and head-mounted pointers
replace mice. These are only a few of the assistive technologies users
may add on to their systems.
