Computer accessibility refers to the accessibility of a computer system to all people, regardless of disability type or severity of impairment. The term accessibility is most often used in reference to specialized hardware or software, or a combination of both, designed to enable the use of a computer by a person with a disability or impairment.

Accessibility is often abbreviated as the numeronym a11y, where the number 11 refers to the number of letters omitted. This parallels the abbreviations of internationalization and localization as i18n and l10n, respectively. Moreover, a11y is also listed on the USPTO Supplemental Register under Accessibility Now, Inc.

Accessibility features are meant to make the use of technology less challenging for those with disabilities. Common accessibility features include text-to-speech, closed-captioning, and keyboard shortcuts. More specific technologies that need additional hardware are referred to as assistive technology.

There are many disabilities or impairments that can be a barrier to effective computer use. Some of these impairments, which can be acquired from disease, trauma, or congenital disorders, include:

A topic closely linked to computer accessibility is web accessibility. Similar to computer accessibility, web accessibility is the practice of making the use of the World Wide Web easier to use for individuals with disabilities.

The biggest challenge in computer accessibility is to make resources accessible to people with cognitive disabilities—particularly those with poor communication and reading skills. For example, people with learning disabilities may rely on proprietary symbols and identify particular products via the product's symbols or icons. Unfortunately, copyright laws can limit icon or symbol release to web-based programs and websites by owners who are unwilling to release them to the public.

In these situations, an alternative approach for users who want to access public computer-based terminals in libraries, ATMs, and information kiosks is for the user to present a token to the computer terminal - such as a smart card - that has configuration information to adjust the computer speed, text size, etc. to their particular needs.

This concept is encompassed by the CEN standard "Identification card systems – Human-machine interface". This development of this standard has been supported in Europe by SNAPI and has been successfully incorporated into the Local Authority Smartcards Standards e-Organisation (LASSeO) specifications.