The W3C's Web Content Accessibility Guidelines (WCAG) define how to make web content more accessible to people with disabilities. Accessibility involves a wide range of disabilities, including visual, auditory, physical, speech, cognitive, language, learning, and neurological disabilities. If a website passes the Guidelines it is accessible to people with a wide variety of disabilities.

Duke is striving for Web Content Accessibility Guidelines (WCAG) 2.0 AA compliance.  

Deconstructing the acronym

WCAG = Web Content Accessibility Guidelines
2.1 = version 2.1
AA = conformance level or how strict the rules are

One practical example:

WCAG Guideline 1.4.3 concerns making text easily legible. It requires that the text color and background colors meet a minimum contrast ratio.

  • Level A - no minimum contrast ratio. (no minimum)
  • Level AA - normal size text must have a contrast ratio of 4.5:1. (medium contrast)
  • Level AAA - normal size text must have a contrast ratio of 7:1. (high contrast)

Measuring compliance

WCAG provides accessibility criteria. It is divided into four principles. Each principle has a set of guidelines with testable success criteria.  The four principles with guidelines are:


A website or app can be viewed by people with very different types of perceptive preferences and needs. The site must give alternatives if a user cannot use one of their senses.

  1. Text Alternatives - Provide text alternatives for any non-text content
  2. Multimedia - Provide video captions and other alternatives for time-based media.
  3. Adaptable - Create content that can be presented in different ways (for example simpler layout) without losing information or structure
  4. Distinguishable - Make it easier for users to see and hear content.

Practical example: One example is a person without perfect vision. The site text must have high enough contrast against its background so that it is easily legible.


A visitor can come to a website with a wide variety of abilities, browsers, devices, and assistive technologies. Interface components and navigation elements need to work in a wide variety of scenarios in a way that everyone can “operate” on it.

  1. Keyboard Accessible - Make all functionality available from a keyboard.
  2. Enough Time - Provide users enough time to read and use content.
  3. Seizures and Physical Reactions - Do not design content in a way that is known to cause seizures or physical reactions.
  4. Navigable - Provide ways to help users navigate, find content, and determine where they are.
  5. Input Options - Make it easier for users to operate functionality through touch and voice activation.

Practical example: Some people cannot use a mouse, so a website needs to be accessible via the keyboard.


If a user does not understand what a site is talking about, or if it makes them feel lost, it has a problem. The site design and user interface should be clear and understandable.

  1. Readable - Make text content readable and understandable.
  2. Predictable - Make Web pages appear and operate in predictable ways.
  3. Input Assistance - Help users avoid and correct mistakes.

Practical example: Making content easy to read is one way to make a website understandable. Other methods include site feedback like instructions to complete a form or an error message if a field is missed.


Technology evolves in ways we cannot predict. New devices, browsers, and functionality come out regularly. Developers must keep up with these changes to ensure a robust site.

  1. Compatible - Maximize compatibility with current and future user agents, including assistive technologies.

Practical example: Validate code and test functionality regularly so it can be transmitted on different systems, screens, and devices.