Joomla 4/5 User Manual
Validating against accessibility standards
To ensure that your pages will be accessible by virtually anyone wishes to access them, you need to validate your pages against accessibility standards. The easiest way to do this is to use one of the many online accessibility validators provided by accessibility support groups. Simply type accessibility validator at your preferred search engine to find one.
Joomla 4 includes an Accessibility Checker plugin. See https://joomla-projects.github.io/joomla-a11y-checker/index.html for more information.