Accessibility (a11y)

Accessibility (a11y) is a measure of a computer system's accessibility is to all people, including those with disabilities or impairments. It concerns both software and hardware and how they are configured in order to enable a disabled or impaired person to use that computer system successfully.

The word accessibility is abbreviated to "a11y," with the number eleven in the middle referring to the number of letters that the word contains between the first and last letter. It follows an Information and Communications Technology (ICT)-oriented convention, just like internationalization (i18n) and localization (l10n), which are used mostly in the software community.

When people talk about "accessible" PDF files, they usually are referring to "tagged" PDF files, even though there is more to an accessible PDF than tags. PDF tags provide a hidden structured, textual representation of the PDF content that is presented to screen readers. They exist for accessibility purposes only and have no visible effect on the PDF file.

HTML tags and PDF tags often use similar tag names (e.g., both have tags named h1) and organization structures, but they really are quite different. If you are comfortable with HTML, you will probably have an easier time creating and editing tagged PDF files.

Videos should be produced and delivered in ways that ensure that all members of the audience can access their content. An accessible video includes captions, a transcript, and audio description and is delivered in an accessible media player.