WCAG Overview

What is WCAG

The Web Content Accessibility Guidelines (WCAG) are developed through the World Wide Web Consortium (W3C) process in cooperation with individuals and organizations around the world. The goal of WCAG is to provide a single shared source of guidance for web content accessibility that meets the needs of individuals, organizations, and governments internationally.

The WCAG documents explain how to make web content more accessible to people with disabilities. Web “content” generally refers to the information in a web page or web application, including: natural information such as text, images, sounds, and code or markup that defines structure, presentation, etc.

The Guidelines are comprised of 78 Success Criteria that define specific guidance for making the web or applications accessible.

Layers of Guidance


The Guidelines and Success Criteria are organized around four Principles that lay the foundation necessary for anyone to access and use web content. Under each of the principles are Guidelines and Success Criteria that help to address these principles for people with disabilities.


Under each principle there is a list of Guidelines that address the Principle. There are a total of 13 Guidelines that are designed to ensure content is directly accessible to as many people as possible. One of the key objectives of the Guidelines is to influence the development of content that is capable of being represented in different forms to match different peoples' sensory, physical and cognitive abilities.

Success Criteria:

Under each Guideline, there are Success Criteria that describe specifically what must be achieved in order to meet the Guideline. Each Success Criterion is written as a statement that will be either true or false when specific web content is tested against it. While some of the testing can be automated using software evaluation programs, others require human testers for part or all of the test. The Success Criteria are written to be technology-neutral and testable.

Although content may satisfy the Success Criteria, the content may not always be usable by people with a wide variety of disabilities. Usability testing aims to determine how well people can use the content for its intended purpose, and should be conducted by those who understand how people with different types of disabilities use the web. It is recommended that users with disabilities be included in test groups when performing human testing.

Conformance Level:

When targeting a specific conformance level, it is helpful to have a checklist to work through the individual Success Criteria. However, keep in mind that all the WCAG Success Criteria are important, and these are things that should be considered when developing web content and applications to ensure accessibility.

  • Level A Success Criteria are those which will have a high impact on a broad array of user populations. In other words, they (usually) don’t focus on one type of disability only. They will also have the lowest impact on the presentation logic and business logic of the site or application. Finally, implementation of these requirements will typically be the easiest.
  • Level AA Success Criteria will also have a high impact for users. Sometimes only specific user populations will be impacted, but the impact is important. Adherence to these Success Criteria may impose changes to a system or site’s presentation logic or business logic.
  • Level AAA Success Criteria are often focused on improvements for specific user populations. They may be difficult or expensive to adhere to, depending on platform limitations.

Naming Convention:

The Guidelines follow a naming convention to help a writer, developer, or designer identify which Success Criterion they are referencing. As an example, we will look at “2.4.3 Focus Order - Level A.” Each part of the name serves a purpose. The following list explains each part of the name:

2 = Principle #2, Operable
4 = Guideline #4, Navigable
3 = Success Criteria #3,
Focus Order = The Title of the Success Criterion
Level A = The Conformance Level of the Success Criterion

For a visual representation of this explanation, please see the following graphic:

An example of the WCAG naming convention for Success Criterion “2.4.3 Focus Order - Level A.” From left-to-right, labeled arrows are pointing to each part of the name as follows: “2” represents the Principle, “4” represents the Guideline, “3” represents the Success Criteria, “Focus Order” is the title and “Level A” is the conformance level.