What Is Web Accessibility?

In web design, accessibility means building your site so everyone can use it, including people with disabilities such as vision, hearing, physical (motor), and cognitive impairments. Many of these visitors browse with assistive technology, like screen readers that read a page aloud, and those tools only work on sites built to support them.

For example, if your site includes videos, people who are deaf or hard of hearing will benefit from captions, which cover not just dialogue but also who is speaking and meaningful sounds.

Why web accessibility matters

The audience is larger than most site owners assume. The World Health Organization's disability fact sheet (March 7, 2023) estimates that 1.3 billion people, 16% of the world's population, experience significant disability. That's 1 in 6 of your potential visitors, and an inaccessible site turns them away at the door.

Accessible design also benefits people without disabilities, such as users on phones with small screens or slow connections. Cross-device layout itself, though, is the job of responsive design, a related but separate practice.

Common accessibility features

The features that make a site accessible are concrete and checkable. These are the core ones:

1. Alt text on every meaningful image, so screen readers can describe it
2. Text contrast strong enough to meet WCAG level AA
3. A visible label on every form field
4. Full keyboard operability, because many people can't use a mouse
5. Captions or transcripts for audio and video
6. Readable fonts and consistent navigation

Automated scans flag the first three most often, as the numbers below show. Frequent doesn't mean most important, though. Work through the whole list, test keyboard access early, and follow every automated check with manual and assistive-technology testing.

The WCAG standard

The W3C's Web Content Accessibility Guidelines (WCAG) define what "accessible" means in practice. The current version is WCAG 2.2, published in 2023. Every requirement traces back to 4 principles, described here in plain language:

• Perceivable: users can take the content in (alt text and captions live here)
• Operable: users can navigate and interact, including by keyboard alone
• Understandable: pages and controls behave predictably
• Compatible with assistive technology: the code works with current and future browsers, screen readers, and other user tools

WCAG defines 3 conformance levels: A, AA, and AAA. Level AA is the target most laws, audits, and lawsuits reference, and it's the one to aim for. Full AAA conformance is rare; WebAIM notes that neither its own site nor the WCAG website claims it.

Where most websites fail

On a handful of basics, measurably. WebAIM's Million report (February 2026) ran automated checks on the top 1,000,000 homepages and found detectable WCAG 2 failures on 95.9% of them, averaging 56.1 errors per page. Six error types account for 96% of everything detected, led by low-contrast text (on 83.9% of homepages), missing image alt text (53.1%), and missing form labels (51%).

Those counts cover only what automated tools can detect. Barriers like broken keyboard navigation never show up in them, so treat the scan results as the most frequent errors, not the full list. Manual testing, covered below, finds the rest.

Accessibility laws and lawsuits

In much of the world, accessibility is a legal requirement, not a courtesy. US plaintiffs filed 3,117 website accessibility lawsuits in federal court in 2025, up 27% from 2024, according to law firm Seyfarth Shaw's ADA Title III tracker (March 2026), and state courts add more. UsableNet's 2025 lawsuit report found WCAG 2.1 AA is the standard those suits most often demand. Section 508 requires accessible sites from US federal agencies, and the EU's European Accessibility Act has applied to many private-sector services, including ecommerce, since June 28, 2025.

Requirements vary by country and sector, so identify the law that covers you and the WCAG version it specifies, then test your site for conformance with that version at level AA. Conformance is the benchmark most of these rules point to, but by itself it isn't a universal guarantee of legal compliance.

Accessibility vs. usability

Accessibility asks whether people with disabilities can use your site at all. Usability asks how easy and efficient the site is for everyone. The two overlap, and accessibility belongs inside your broader user experience (UX) work: a site can't offer a good experience to someone who can't operate it.

How to test your site

Start with a free automated checker: WebAIM's WAVE, Google's Lighthouse, or axe DevTools. Keep their limit in mind, though. WebAIM states it plainly in its own methodology: automated tools catch only a subset of WCAG failures, so a clean scan doesn't mean an accessible site.

Then add 2 manual checks anyone can run. Put the mouse aside and press Tab through the page: can you reach and operate every link, menu, and form? Next, spot-check with a screen reader: NVDA is free on Windows, and VoiceOver is built into macOS. For step-by-step fixes, see our guide to designing an accessible website.