- W3C WAI guidelines, 1.0
- Content is accessible when it may be used by someone with a disability.
- ANSI HFES 200 (draft)
- The set of properties that allows a product, service or facility to be used by people with a wide range of capabilities, either directly or in conjunction with assistive technologies. Although 'accessibility' typically addresses users who have a disability, the concept is not limited to disability issues.
- ISO TS 16071
- The usability of a product, service, environment or facility by people with the widest range of capabilities.