All functionality must be usable with the keyboard. That is, users can access and move between links, buttons, forms, and other controls using the Tab key and other keystrokes. Websites should not require a mouse; for example, pop-up calendars should also let users type in a date.
Many computers and mobile devices today have built in text-to-speech software. Some people with disabilities, including people who are blind, use specialized software called screen readers. Screen readers provide important functionality such as navigating through headings, speaking image alternatives, and identifying internal and external links. They can also highlight the text as it is being read aloud for people to see and hear the content at the same time. Content must be coded properly so that all of the functionality of the text-to-speech software works with the content.