What is Accessibility?


Web accessibility helps ensure that anyone can perceive, understand, navigate, interact with, and contribute to the web (from Web Accessibility in Mind (WebAIM)).

The Worldwide Web Consortium (W3C), an international organization that develops and maintains open standards for the Web has created the Web Content Accessibility Guidelines (WCAG) . These form the basis of most web accessibility law in the world and include four principles:

  • Perceivable: Information and user interface must be available to people in a way they can perceive, either through the browser or assistive technologies (e.g. screen readers, screen enlargers, etc.)
  • Operable: The user interface is usable, including all controls and interactive elements using either the mouse, keyboard, or an assistive device.
  • Understandable: Content is clear and limits confusion and ambiguity.
  • Robust: A wide range of technologies (including old and new) can be used to access the content (from WebAIM).

Accessibility applies to both websites and the documents, images, video, sound, an other materials that reside on those sites, and this site will cover best practices for both.

Inclusivity and Universal Design

Implementing accessibility standards ensures that people with hearing, visual, motor, and cognitive disabilities can use and interact with your materials. In addition, accessible sites can be used on any device, whether it’s a mobile phone, tablet, or computer. Ensuring your websites and materials are accessible often makes them easier to use and understood by all users.

Examples of accessibility in practice:

  • Using captioning for video and audio allows people with hearing impairments to access the audio content;  it also allows people working in libraries or other quiet spaces to read the content without needing headphones.
  • Adding alt text to images is important for people who are blind or visually impaired using screen readers. It also helps people with a slow internet connection or while browsing on a mobile device with images turned off to save bandwidth.
  • Using bold rather than red for emphasis ensures legibility for people with color blindness, as well as for many other readers regardless of vision levels.


In the United States, accessibility is established by law, in the Americans with Disabilities Act (ADA) of 1990 and the Rehabilitation Act of 1973.

Additional Resources

Below you will find a number of different resources to learn more about accessibility.


CUNY & OpenLab



Information on this page is adapted from: