Digital Accessibility Blog

WCAG 2.1 Principles Explained: Understandability

Written by David | Jul 24, 2018

In order for a website to be compatible with the WCAG 2.1 principle of understandability, developers need to be sure the website is:

  • Readable - Web content should identifying the language(s)that text is written in as well as any unusual words or abbreviations.
  • Predictable -Content is in a predictable order so people with disabilities can successfully use andnavigatethe site.
  • Input Assistance -Assistive technologies can make mistakes when entering information. Therefore websites should provide better error messages and help prevent errors whenever possible.

The Web Content Accessibility Guidelines (WCAG) are a detailed set of standards for making websites and other online content more accessible to people with disabilities. This article will discuss the third pillar of the WCAG standards: understandability.

The Understandability Principle

Content that is understandable can be read and comprehended by users without undue effort. This means that the content should be understandable both by the users themselves and by assistive technologies such as screen readers.

Understandability is particularly important for three types of people with disabilities:

  • People with visual disabilities who rely on screen readers and braille displays to understand the text of a website.
  • People with learning disabilities who have difficulties with long, complex sentences and advanced vocabulary words.
  • People with cognitive disabilities who have difficulties focusing on long paragraphs of text.

In the WCAG 2.0, understandability is divided into three areas of concern:

  • Readable: Some people with disabilities experience challenges when recognizing written words or when inferring the meaning of a word from context. Your web content should make this process as easy as possible by identifying the language(s) that text is written in as well as any unusual words or abbreviations.
  • Predictable: Presenting your website content in a predictable order and having your site behave predictably are essential for people with disabilities to successfully use and navigate your site.
  • Input Assistance: People with disabilities, and the assistive technologies they use, often make mistakes more easily when entering information. In order for them to understand the problem and correct the issue, websites should provide better error messages and help prevent errors whenever possible.

What Developers Should Know About Understandability

Setting the natural language of a web page or section can be done through lang attributes in HTML. For example, to set the language of a page to American English, use the code <html lang="en-US"> at the beginning of your HTML.

Sections of text in a foreign language, such as loanwords and quotations, should also be demarcated using the lang attribute. This will help screen readers know how to vocalize these portions of the text.

Defining unusual expressions and abbreviations is usually best done by redirecting users to a dedicated glossary.

In most cases, organizations choose to satisfy the input assistance criteria for understandability by using HTML5 and/or JavaScript to implement client-side error detection and error handling.

Understandability in WCAG 2.1

WCAG 2.0 was published in 2008, and has been the most important and influential accessibility standard ever since. However, the guidelines had not evolved in the decade since their release. In the meantime, mobile devices, responsive design, and new web technologies have all affected the way that people interact with online content. For these reasons, the WCAG authors released WCAG 2.1 in June 2018, the first substantial update to the guidelines in 10 years.

Unlike the other three WCAG principles, understandability has not received any new guidelines or updates in WCAG 2.1. Because WCAG 2.1 remains backwards-compatible with WCAG 2.0, however, all of the old guidelines for understandability are still in force.

Final Thoughts

Although technological change has not affected it as much as the other three WCAG principles, making your website understandable remains a core obligation for internet accessibility. To learn more about what WCAG 2.1 means for your business, follow the Bureau of Internet Accessibility blog or contact us for a free 30-minute consultation with our accessibility experts.
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