WCAG 2.0 vs 2.1
The World Wide Web Consortium (W3C) and Web Accessibility Initiative (WAI) are responsible for the creation, maintenance, and updates for WCAG. WCAG is regularly reviewed and updated to reflect a continuous process of improving accessibility and in reaction to advancements in technology and web content development. Each update is numbered with two digits, separated by a period. The first digit represents the major version number, and the second digit represents the minor version number.
The Accessibility for Ontarians with Disabilities Act (AODA) requires only WCAG 2.0 conformance at present. Given the versions of WCAG that are currently published and the broad use of touch screen technology, it is a good idea to start aiming for WCAG 2.1 now. This will prepare your website for the near future and WCAG 2.1 adds success criteria related to touch screens. Keep in mind that WCAG 2.2 and WCAG 3.0 are also being drafted currently and are coming soon.
Levels A, AA, and AAA
There are a number of success criteria within WCAG. Each success criterion corresponds to a specific aspect of digital accessibility. WCAG denotes three levels of accessibility depending on the number of success criteria that a website satisfies. When a web page satisfies success criteria, we say it is conformant with the criteria (rather than compliant).
The three levels of accessibility, from lowest to highest, are Level A, Level AA, and Level AAA. Level A is basic accessibility, AA is considered very good, and AAA is excellent accessibility. Most organizations aim for Level AA, because sometimes it is not possible to satisfy every Level AAA success criterion. Even if your content is only required to be Level AA conformant, it is good practice to document any Level AAA features.
Table 1 below shows the number of success criteria that must be satisfied to achieve the different levels of accessibility associated with WCAG 2.0 and 2.1.
| Level A | Level AA | Level AAA | |
| WCAG 2.0 | 25 Success Criteria | 13 Success Criteria | 23 Success Criteria |
| WCAG 2.1 | 30 Success Criteria | 20 Success Criteria | 28 Success Criteria |
- For a web page to meet Level A – it must satisfy all of the Level A Success Criteria.
- For a web page to meet Level AA – it must satisfy all of the Level A Success Criteria and all of the Level AA Success Criteria.
- For a web page to meet Level AAA – it must satisfy all of the Level A Success Criteria, all of the Level AA Success Criteria, and all of the Level AAA Success Criteria.
Success Criteria
Success Criteria are written in clear language and are designed to be testable. This means that it is clearly identifiable if web content conforms to or fails a specific criterion. For example, Success criterion 1.1.1 states that “All non-text content that is presented to the user has a text alternative that serves the equivalent purpose, except for [certain situations].” Based on this, someone can examine all non-text content and confirm that this criterion is met, or not
Typically, testing is done through a combination of automated testing and human evaluation (more on testing on page). Formal testing can also be complemented by usability testing, where users with disabilities interact with the web content and can give direct feedback on what does and does not work for them. Typically, testing is done through a combination of automated testing and human evaluation. See the Ways of Testing page for more information. Formal testing can also be complemented by usability testing, where users with disabilities interact with web content and can give direct feedback on what does and does not work for them.
All Success Criteria can be found on the WCAG Quick Reference.
Techniques and Failures
For each of the Success Criteria, WCAG provides additional information, including sufficient and advisory techniques, and example failures. This additional information is to support you through the process of meeting the Success Criteria:
- Sufficient Techniques are reliable ways to meet the success criteria. You can use other techniques not listed, if they work. See: Sufficient Techniques.
- Advisory Techniques are suggested ways to improve accessibility, but they are not required. See: Advisory Techniques.
- Failures are test results which show success criteria were not met. See: Failures.
More detail is available on the “Understanding Techniques for WCAG Success Criteria” page.
Normative vs. Informative
It is important to keep in mind that the sufficient and advisory techniques are provided as additional information to support you in meeting the criteria. As described in WCAG, techniques are informative which means that you do not need to use any specific technique, as long as you use one that works.
On the other hand, all Success Criteria are normative – this means that your web pages must meet them in order to be conformant with WCAG.