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Web Accessibility for SEO: A WCAG 2.1 Compliance Guide

Web accessibility means your site works for everyone — including people who use screen readers, keyboard navigation, or need high contrast text. Accessibility is not just the right thing to do — many of the fixes directly improve your SEO, and in the UK the Equality Act 2010 requires reasonable adjustments for disabled users.

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What is web accessibility and who does it affect?

Web accessibility means designing and building websites that people with disabilities can use. This includes people who are blind or visually impaired (using screen readers), deaf, have motor difficulties (using keyboard navigation instead of a mouse), or have cognitive disabilities. In the UK, approximately 1 in 5 people have some form of disability.

Legal requirement: In the UK, the Equality Act 2010 requires websites to make reasonable adjustments for disabled users. Public sector websites must meet WCAG 2.1 AA by law. Private sector sites face legal risk from disability discrimination complaints.

The most common WCAG violations and how to fix them

1. Images without alt text (WCAG 1.1.1 — Level A)

Every image that conveys information needs an alt attribute. Screen readers read the alt text aloud. Google uses it to index and rank images. Fix: add alt="description of what the image shows" to every img tag. Decorative images should have alt="" (empty) so screen readers skip them.

2. Form inputs without labels (WCAG 1.3.1 — Level A)

Every form input needs an associated label element. Placeholder text is not a substitute — it disappears when the user starts typing. Fix: add <label for="input-id">Field name</label> before each input, matching the input's id attribute.

3. Low colour contrast (WCAG 1.4.3 — Level AA)

Text must have sufficient contrast against its background. Light grey text on white fails. Fix: use the Accessibility Checker to find failing elements, then darken the text colour until it passes the 4.5:1 ratio requirement.

4. Missing skip navigation link (WCAG 2.4.1 — Level A)

Keyboard users must tab through every navigation item on every page unless a skip link is provided. Fix: add <a href="#main-content" class="skip-link">Skip to main content</a> as the very first element in your HTML, visible on keyboard focus.

Quickest win: Add alt text to every image that does not have it. This fixes the most common WCAG violation, improves Google image indexing, and takes seconds per image.

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