Website accessibility: a practical guide

Website accessibility means building a site that people can use regardless of ability — including those who navigate by keyboard, use a screen reader, have low vision or colour blindness, or simply need larger text. It is often treated as a niche add-on. It should not be: an accessible site is a better site for everyone, and getting the basics right is neither hard nor expensive when it is designed in from the start.

What accessibility is

Accessibility is usually measured against the Web Content Accessibility Guidelines (WCAG) — an international standard, organised around four principles: content should be perceivable, operable, understandable and robust. In plain terms, people must be able to perceive your content (e.g. text alternatives for images), operate the site (e.g. by keyboard, not just a mouse), understand it (clear language and structure), and rely on it working with assistive technologies. WCAG has levels (A, AA, AAA); AA is the common target.

Why it matters

Four reasons, all real. It is ethical — excluding people from your site is not acceptable when it is avoidable. It is commercial — a significant share of the population has a disability, and an inaccessible site turns them away. It overlaps with SEO and UX — semantic structure, alt text, clear headings and keyboard operability help search engines and all users, not only those using assistive tech. And it is increasingly a legal expectation — many jurisdictions require it, and the requirements are tightening. Confirm the specific obligations that apply to your business, as they vary by location and sector.

The essentials

You do not need to be an expert to cover the fundamentals. The highest-impact basics:

• Semantic HTML. Use real headings, lists, buttons and landmarks — structure that assistive tech understands.
• Alt text. Describe meaningful images; mark decorative ones as decorative.
• Keyboard operability. Everything usable with a mouse must work with a keyboard, with a visible focus state.
• Colour contrast. Enough contrast between text and background that low-vision users can read it.
• Labels and headings. Form fields labelled, a logical heading hierarchy, links that make sense out of context.
• Respect user preferences. Don’t trap people in motion or tiny text; support reduced-motion and resizing.

Common failures

The same handful of problems account for most accessibility failures: images with no alt text, poor colour contrast, forms with unlabelled fields, content that only works with a mouse, missing focus states, headings used for styling rather than structure, and auto-playing media. None is hard to fix; all are common, precisely because accessibility was treated as an afterthought rather than designed in. The cheapest time to get it right is while building; retrofitting is harder.

How to check your site

Start with automated tools — browser extensions and online checkers catch a good share of issues quickly — but know their limit: they find perhaps half of the problems. The rest need human checks: navigate your whole site using only the keyboard, try it with a screen reader, and review contrast and content structure. Combine automated scanning with manual testing, fix the issues by priority, and build accessibility into how you work rather than auditing it once and forgetting. Our website design pillar guide puts it in the wider context of building a site well.

Frequently asked questions