According to the World Wide Web Consortium, the intent of Web Content Accessibility Guideline 3.1 is to allow text content to be read and understood by users.
WCAG 3.1 Readable

The WCAG specification
According to the World Wide Web Consortium, the intent of Web Content Accessibility Guideline 3.1 is to allow text content to be read and understood by users.
Our previous blog on iPhone accessibility covered features that are useful for people who are blind or have low vision. This week, we continue the discussion and examine iOS features that can help people with hearing loss to participate in everyday activities independently.
One of the Level AAA Success Criteria of the Web Content Accessibility Guidelines (WCAG) states that the target for pointer inputs like buttons, links, and other clickable elements should be at least 44 by 44 CSS pixels in size.
Great care should be taken into account when designing the user interface and user experiences of websites and applications to ensure their presentation is easy to follow from the first use, including for people with disabilities.
One of the most essential assistive technologies out there is screen reading software, which allows people with sight loss, cognitive or learning disabilities, or who are deaf and blind to use a computer.
PDFs are considered universal documents: regardless of what software or device someone is using, they will be able to open a PDF file. But this doesn’t mean they will be able to read the PDF if the necessary accessibility features are missing.