Users must be able to understand the information as well as the operation of the user interface (the content or operation cannot be beyond their understanding).

Information and user interface components must be presentable to users in ways they can perceive. This means that users must be able to perceive the information being presented (it can't be invisible to all of their senses).

17 Guidelines

Is your Content Understandable?

The questions below are designed to assist you in determining if your website, application, and/or content is understandable to people with disabilities. Each question is linked to in-depth information, resources, and examples on how to apply the guidelines to our products.

Language of Page:

Is the language of each page properly identified in the code for your web site/application? (Success Criterion 3.1.1 – Level A)

Language of Parts:

If content on a page switches from one language to another language for a section, is that section’s language properly identified in the code? (Success Criterion 3.1.2 – Level AA)

Unusual Words:

Do you define or provide users access to definitions for any unusual words or topic specific jargon used on your site or application? (Success Criterion 3.1.3 – Level AAA)


Does your site or application provide users with a way to access expanded definitions of any abbreviations and acronyms used? (Success Criterion 3.1.4 – Level AAA)

Reading Level:

Does your site or application provide supplemental content, or lower level reading versions, for content that is above the lower secondary education level? (Success Criterion 3.1.5 – Level AAA)


If the content on your site or application contains words which pronunciation is vital to understand the meaning, is there a way for users to get the proper pronunciation of those words? (Success Criterion 3.1.6 – Level AAA)

On Focus:

Have you ensured that user interface components contained within your site or application do not initiate a change of context when they receive focus? (Success Criterion 3.2.1 – Level A)

On Input:

In your site or application, are there controls (e.g., form fields, radio buttons or checkboxes) that cause an unexpected change in context when answered? If so, are you providing users with notification of changes? (Success Criterion 3.2.2 – Level A)

Consistent Navigation:

In your website/application, when navigational mechanisms are repeated from page to page, are they consistent in location and order across all similar pages? (Success Criterion 3.2.3 – Level AA)

Consistent Identification:

Do you provide consistent labels and alternative text for like / repetitive components? (Success Criterion 3.2.4 – Level AA)

Change on Request:

Are you providing user controls to initiate visual changes in context, or providing notification of context changes within your website/application? (Success Criterion 3.2.5 – Level AAA)

Error Identification:

If an input error occurs in your website/application, is the error identified and described to the user in text form? (Success Criterion 3.3.1 – Level A)

Labels or Instructions:

In your website/application, do input fields have sufficient labeling and instructions describing what input data is expected? (Success Criterion 3.3.2 – Level A)

Error Suggestion:

If an input error occurs in your website/application, do you provide input error correction suggestions to the user, if suggestions are known? (Success Criterion 3.3.3 – Level AA)

Error Prevention (Legal, Financial, Data):

In your website/application, do you provide a way for a user to reverse a submission, correct input errors, or confirm data before final submission of legal, financial, or data (test response data)? (Success Criterion 3.3.4 – Level AA)


In your website/application, do you provide context-sensitive help on how to perform operations when the label is not sufficient to explain the context? (Success Criterion 3.3.5 – Level AAA)

Error Prevention (All):

In your website/application, do you provide a way for a user to reverse a submission, correct input errors, or confirm data before final submission? (Success Criterion 3.3.6 – Level AAA)