Web accessibility describes the extent to which websites, tools, and technologies are accessible to individuals with disabilities who may rely on keyboard-only navigation, screen readers, closed captions, and other avenues for consuming information. Ideally, all web technologies will be accessible to people despite auditory, cognitive, neurological, speech, physical, or visual disabilities.
Standards for web accessibility have defined most notably by W3C’s Web Content Accessibility Guidelines (WCAG). According to W3C, accessible content must observe the four principles of accessibility:
- Perceivability: Information must be presented in a way that users can perceive. For instance, a blind person will need an alternative description of an image on a webpage because they cannot take this information in visually.
- Operability: Users must be able to operate a particular web interface. For instance, someone with hand tremors or limited mobility should be able to use their keyboard to navigate through a website, select links, and fill out forms.
- Understandability: Web content should be understandable to users. For example, complex information should be stated without use of jargon and unclear wording.
- Robustness: Web content should be robust enough that it can be accessed with a range of technologies that may change or evolve over the course of time. For instance, an ebook should be accessible via various web browsers or screen readers, not just one.