WCAG definition
Web accessibility is the practice of designing and building websites and apps that people with disabilities can perceive, understand, navigate and use, including people who are blind, deaf, have motor impairments or cognitive differences. The Web Content Accessibility Guidelines (WCAG), published by the W3C, are the international standard used to measure it.
What is WCAG?
WCAG is published by the W3C's Web Accessibility Initiative. Version 2.0 arrived in 2008, 2.1 in 2018 and 2.2 in 2023, each adding success criteria while keeping earlier ones. Criteria are graded at three levels: A, AA and AAA. Level AA is the usual target in laws, public procurement and corporate policies, and it covers the barriers that block the most users.
- Perceivable: text alternatives, captions and sufficient color contrast.
- Operable: everything works by keyboard, with enough time and no seizure-inducing flashes.
- Understandable: readable text, predictable behavior and helpful form errors.
- Robust: markup that assistive technologies such as screen readers can interpret.
Common accessibility failures
Most problems are basic and fixable. Automated scans of popular websites repeatedly find the same handful of issues, and they are as easy to avoid in a new build as they are tedious to retrofit later. Fixing them helps every user, not only disabled people.
- Images without meaningful alt text.
- Text with low contrast; WCAG AA asks for 4.5:1 for normal-size text.
- Form fields without labels, and errors shown only in red.
- Clickable divs instead of real buttons and links, so keyboards cannot reach them.
- Missing or invisible focus indicators.
- Videos without captions and audio without transcripts.
- Content that cannot be zoomed to 200 percent without breaking the layout.
- Carousels and time limits that users cannot pause or extend.
- Error messages that are not announced to screen readers.
Accessibility laws and regulations
In the United States, websites of businesses open to the public face lawsuits under the Americans with Disabilities Act, and Section 508 covers federal agencies and their suppliers. The European Accessibility Act applies to many consumer products and services, including ecommerce and banking, from June 2025, with EN 301 549 as the technical standard. In India, the Rights of Persons with Disabilities Act and government web guidelines set requirements for public sector sites. Public sector bodies in many countries must also publish accessibility statements.
How to test for accessibility
Automated tools such as axe, Lighthouse and WAVE catch issues like missing labels and contrast problems quickly, and they belong in CI. They cannot judge whether alt text is meaningful or whether a flow makes sense, so manual checks are essential: complete every key task using only the keyboard, then with a screen reader such as NVDA, JAWS, VoiceOver or TalkBack. Testing with disabled users reveals what checklists miss. Repeat checks whenever key flows change.
How to build accessible websites
Start with semantic HTML: real buttons, links, headings, lists and labeled inputs give most accessibility for free. Use ARIA only to fill genuine gaps, because incorrect ARIA can make things worse. Build accessibility into the design system so every team reuses tested components, and include it in design reviews and acceptance criteria. Nexzem audits sites against WCAG 2.2 AA and fixes issues at the component level, so each improvement reaches every page that uses that component at once.