Web Content Accessibility Guidelines (WCAG)

Web Content Accessibility Guidelines (WCAG) covers a wide range of recommendations for making Web content more accessible. Following the guidelines will make content more accessible to a wider range of people with disabilities, including requirements for people with sensory, physical and cognitive impairments; but will they do not address every user need for people with these disabilities. The guidelines address accessibility of web content on desktops, laptops, tablets, and mobile devices. Following these guidelines will also often make Web content more usable to people in general.


  • WCAG defines the needs of people with disabilities to access electronic content.
  • Organized by Principles (4), Guidelines (13) and Success Criteria (78).
  • Success criteria are the real requirements with three levels of priority: A (Highest), AA and AAA (lowest).  A and AA priorities are the basis of most standards.
  • While inspired by HTML, WCAG is designed to be technology agnostic and does not tell people how to comply with a specific technology.
  • WCAG conformance is defined by accessibility and not usability.  While accessibility typically increase usability, websites that meet the conformance criteria of WCAG are not necessarily going to be more usable.

Why is WCAG important?

The W3C Web Content Accessibility Guidelines are the basis of national and international web accessibility compliance standards, including the U.S. Section 508 information Technology Accessibility and the Illinois Information Technology Accessibility Act.  WCAG helps people understand the issues of making electronic information accessible and basic knowledge of the requirements is important to be able to effectively evaluate information technologies for accessibility and include accessibility features in the design and development.

Understanding WCAG and Universal Design

The requirements of WCAG are based on the principles of Universal Design, but since the document was designed to be used for regulatory purposes the conformance criteria is defined in a more mechanical way.   What this means is a website can meet the conformance requirements of WCAG without really being usable to people with disabilities.   Sometimes this is due to the original design of a website not being very usable to anyone, and so adding accessibility features makes it more accessible to people with disabilities but the website is still difficult to use.  Most often it is due to not including accessibility features in the planning and design stages of websites and online applications.

Accessible Design vs. Accessible Repair

An analogy for electronic accessibility can be found in sidewalk curb cuts.  Not including curb cuts in sidewalks when sidewalks are poured requires a time consuming and expensive process of going back and jack hammering out the existing concrete and then re-pouring concrete with the curbcuts.   When  curb cuts are included in the original construction there is little or no extra expense to including them and people with disabilities benefit immediately to the accessible sidewalk.

Unfortunately accessible repair is where we sit with most online resources, accessibility is usually not considered during the design or development of online applications  and when the accessibility issues are discovered it creates and expensive and time consuming effort to fix the issues, so the issues are often cherry picked for importance and resources available.  Accessible repair gives accessibility a bad name.  The problem is compounded by the  continuous development model used for most online applications where accessibility fixes compete with other bug fixes and new feature development.

When the requirements of WCAG are considered in the initial design and quality assurance processes there is little if any additional costs for the inclusion of accessibility and new features are accessible as they are developed. People with disabilities do not have to wait or be frustrated with limited or difficult access online applications which creates a more inclusive environment for learning and working.

Authoring Universally Accessible Content

For the web to fulfill it’s potential for everyone, authors need to understand more about how their authoring techniques impact people with disabilities.  Most content is not created by experienced and trained web professionals, but by people with a range of skills and experience with user accounts that give them access to the page creation and editing features of a content or learning management systems.   In order for these people to create accessible content they need to understand the features of universal design and WCAG and also how their authoring environment allows them to add accessibility information.  These are clearly two big steps for most people who may also be only occasional contributors to online content.

The key to helping authors is to create authoring tools that make it easier to create accessible rather than inaccessible content.   The authors tools by their very features guide authors including accessibility information and makes it difficult to use techniques that are inaccessible.

Example of how authoring tools can support authors in creating accessible content:

  1. Warning or not allowing authors to use text styling what does not meet color contrast standards.
  2. When inserting an image in a  content management system, the author would be asked question about the purpose of the image in the document an guide the author in creating an appropriate text description.
  3. When a video is created caption and transcription files are automatically generated and the author is easily able to correct mistakes.
  4. The authoring tool automatically monitors heading levels and only allows headings of certain levels in a portion of the document.

WCAG Organization

WCAG FeatureDescription
4 Principles (POUR)
  1. Perceivable
  2. Operable
  3. Understandable
  4. Robust
13 Guidelines
  1. Perceivable
    1. Text Alternatives
    2. Time-based Media
    3. Adaptable
    4. Distinguishable
  2. Operable
    1. Keyboard Accessible
    2. Enough Time
    3. Seizures
    4. Navigable
    5. Input Modalities (New in WCAG 2.1)
  3. Understandable
    1. Readable
    2. Predictable
    3. Input Assistance
  4. Robust
    1. Compatible
78 Success Criteria
  • Real requirements of WCAG.
  • Three levels of importance:
    • A: Highest priority (29)
    • AA: Next highest (21)
    • AAA: Lowest priority (28)
Table: Overview of the Principles, Guidelines and Success Criteria for W3C Web Content Accessibility Guidelines 2.1.

Participating in WCAG Development

The University of Illinois is a member of the W3C which makes anyone who works for or attends the university eligible to participate in the  W3C WCAG working group, not just working groups related to accessibility.