ONPAGE · SEO GLOSSARY

Web Accessibility and SEO

Web accessibility (making websites usable by people with disabilities) and SEO overlap significantly — alt text, heading hierarchy, semantic HTML, descriptive link text, and keyboard navigability all improve both screen-reader usability and search engine crawlability. Implementing WCAG guidelines typically improves SEO signals as a byproduct.

Definition

Web accessibility standards (WCAG 2.1/2.2 from the W3C) define criteria for making web content usable by people with visual, auditory, motor, and cognitive disabilities. Many of these criteria align directly with SEO best practices: **Alt text (WCAG 1.1.1)**: meaningful alt text on images is required for screen reader users and also provides keyword signal and crawlability to Googlebot. The SEO and accessibility requirements are the same: describe what the image shows. **Heading hierarchy (WCAG 1.3.1)**: correct heading order (H1 → H2 → H3, never skipping levels) is required for screen reader navigation and also provides content structure signals to Googlebot. **Descriptive link text (WCAG 2.4.6)**: links with meaningful anchor text ("view our technical SEO audit checklist") are required for screen reader users who navigate by links and also provide keyword signals in the anchor text. "Click here" links fail both accessibility and SEO. **Semantic HTML (WCAG 1.3.1)**: using <nav>, <main>, <header>, <footer>, <article>, <section> landmark elements helps screen readers identify page regions and also helps Googlebot understand page structure. **Colour contrast (WCAG 1.4.3)**: not a direct SEO factor but contributes to readability, which affects engagement metrics that correlate with rankings. **Keyboard accessibility (WCAG 2.1.1)**: keyboard navigability improves usability for motor-impaired users and for Googlebot, which navigates some pages as a keyboard-only browser. **Form labels (WCAG 1.3.1)**: labelled form inputs improve usability for screen reader users and also help Googlebot understand form purpose. **Page title (WCAG 2.4.2)**: unique, descriptive page titles required for accessibility are also the foundation of SEO title tag optimisation.

Why it matters for SEO

Accessibility improvements made for compliance (WCAG 2.1 AA is increasingly required by regulation — ADA in the US, EN 301 549 in the EU) typically produce measurable SEO benefits as a byproduct: better heading structure, more descriptive alt text, semantic HTML, and improved link text. There is no conflict between accessibility and SEO — they share the same underlying requirement: well-structured, clearly described, semantically meaningful content.

How DeepSEOAnalysis checks this

The audit covers the accessibility-SEO overlap: image alt text presence and quality, heading hierarchy correctness (no skipped levels, one H1 per page), link anchor text descriptiveness (flagging generic "click here" or "read more" anchors), semantic landmark element usage, and page title uniqueness and presence. Full WCAG compliance testing requires dedicated accessibility testing tools (axe, WAVE, Deque) beyond the scope of an SEO audit.

Useful tools and resources

Free SEO audit

GLOSSARY

onpage

Heading Tags (H1–H6)

HTML elements that define the hierarchical structure of page content — H1 for the page title, H2 for main sections, H3 for subsections — used by Google to understand content organisation and topic coverage.

Read definition →

technical

Semantic HTML

Using HTML elements for their intended meaning — `<article>`, `<nav>`, `<header>`, `<main>`, `<section>`, `<aside>`, `<h1>`–`<h6>`, `<figure>`, `<time>` — rather than generic `<div>` containers for all elements. Semantic HTML improves accessibility, crawlability, and Google\'s ability to identify the purpose and hierarchy of page content.

Read definition →

links