What Is WCAG 2.1 AA? A Plain-English Guide for Public Agencies

What A, AA, and AAA Mean

Every WCAG requirement, called a success criterion, is assigned one of three levels. Think of them as floors of a building.

• Level A is the ground floor. These are the basics without which some people cannot use your site at all. Example: video content needs captions for prerecorded audio.
• Level AA is the standard floor. It includes everything in Level A plus requirements that remove the most common, most serious barriers. Example: text needs enough contrast against its background to be readable. This is the level DOJ chose.
• Level AAA is the penthouse. It is the most demanding level, and even the W3C says it is not achievable for all content. The rule does not require it.

When the rule says WCAG 2.1 AA, it means all of Level A plus all of Level AA: 50 success criteria in total. DOJ picked this level because it is the same target used by the federal government's own Section 508 standard, it is widely supported by tools and testing services, and years of court settlements had already made it the de facto benchmark. The department chose a bar that was demanding enough to matter and established enough to be practical.

What WCAG 2.1 AA Asks of Your Website, in Human Terms

You do not need to memorize 50 criteria. Most of the standard comes down to nine practical ideas.

• Text alternatives. Every meaningful image needs a short written description, called alt text, so that a person using a screen reader knows what the image shows. A photo of the new fire station needs words. A purely decorative border does not.
• Keyboard access. Everything a mouse can do, a keyboard must be able to do. Many people with motor disabilities, and all screen reader users, navigate with the Tab key instead of a mouse. If your permit application traps keyboard users halfway through, it fails.
• Color contrast. Text has to stand out clearly from its background. Light gray text on white, or gold on pale yellow, can be unreadable for people with low vision. Contrast is measured with free tools, so this is one of the easiest things to check.
• Captions. Prerecorded videos need accurate captions, and live video, like a streamed council meeting, needs live captions. Auto-generated captions are a starting point, but someone has to fix the errors. "Bored meeting" is not the same as "board meeting."
• Forms and labels. Every field on a form needs a label that screen readers can announce, so a resident knows whether the box they are typing in wants a name, an address, or an account number. This applies to everything from contact forms to utility payments.
• Headings and structure. Pages need real headings, marked up in the code, not just bold text. Screen reader users skim a page by jumping from heading to heading, the same way sighted users skim visually. Good structure helps everyone, including search engines.
• Accessible PDFs and documents. Documents posted on your site count as web content. A scanned PDF is just a photograph of paper, and a screen reader finds nothing in it. Documents need real, selectable text, a logical reading order, and tags that convey structure.
• Clear error messages. When someone makes a mistake on a form, the site has to say what went wrong and where, in text. A field that simply turns red tells a blind user nothing, and tells a colorblind user very little.
• Mobile usability. WCAG 2.1 added requirements for phones and tablets: content must work in portrait and landscape, text must be able to enlarge without breaking the page, and controls must not depend on complex gestures alone.