SEO and Web Accessibility: Overlapping Best Practices

Short answer

Accessibility and SEO overlap wherever a page has to be understood without being seen the way a sighted mouse user sees it: alt text, descriptive link text, real HTML structure, captions and transcripts, readable mobile layouts and fast pages serve people using assistive technology and help search engines interpret the page. The overlap isn't complete, and the reasons differ: some accessibility practices, such as keeping headings in order, matter for people using screen readers but, by Google's account, not for Search. Treat accessibility as a requirement for people first, and take the search benefits where they come with it. For public schools, universities and other state and local government bodies in the U.S., it's also a legal deadline.

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Where the Two Overlap

Element	What it does for accessibility	What it does for search
Alt text	Describes images to screen reader users	Helps Google understand the image, and serves as anchor text for linked images
Descriptive link text	Tells users where a link goes out of context	Tells search engines what the target page is about
Headings	Let screen reader users navigate by section	Make structure clear; Google says heading order doesn't matter to Search
Semantic HTML (nav, main, button, lists)	Lets assistive technology identify parts of the page	Makes content and navigation easier to parse
Captions and transcripts	Make audio and video usable for deaf and hard-of-hearing users	Put the spoken content in indexable text
Mobile-friendly, zoomable layout	Supports low vision and motor needs	Matches how Google indexes (mobile version)
Performance	Helps users on slow devices and connections	Feeds page experience and Core Web Vitals

Alt Text

Google’s image guidance calls alt text the “most important attribute when it comes to providing more metadata for an image” and notes it “also improves accessibility for people who can’t see images on web pages, including users who use screen readers or have low-bandwidth connections.”

Describe what the image shows and why it’s there: “Brown leather messenger bag with brass buckle”, not “image” or a file name.
Leave alt empty (alt="") for purely decorative images, so screen readers skip them.
Don’t stuff keywords; write for a person who can’t see the image.

More detail is in image SEO.

Headings

Use headings as an outline: one main heading for the page topic, and sections and subsections below it in order. That structure is what screen reader users jump between. Google has said heading order doesn’t matter to Google Search, so fix heading structure for users, not for rankings; the details and Google’s own wording are in heading hierarchy.

Link Text

“Click here” and “learn more” fail both groups: a screen reader user listing links hears a column of identical phrases, and a search engine learns nothing about the target. Write link text that names the destination (“download the migration checklist”, “see the product specifications”). Anchor practices for search are in anchor text optimization.

Semantic HTML and ARIA

Use the element for the job: button for actions, a for navigation, nav, main, header, footer and lists for structure, and real table markup with header cells for data.
Use ARIA only where native HTML can’t express something, such as a custom widget; wrong ARIA can make a page harder to use.
Make sure content isn’t only in images or hidden behind interactions that keyboard and screen reader users can’t trigger.

Video, Audio and Forms

Captions on every video, transcripts for audio and video, published as text on the page; see video SEO.
Forms with visible labels tied to each field, clear error messages, and no reliance on color alone.

Mobile and Performance

Text that can be enlarged, tap targets big enough to hit, no content cut off on small screens, and pages that load and respond quickly help people with low vision, tremors or slow devices, and they match how Google indexes and measures pages; see mobile-first indexing and Core Web Vitals.

Standards and Legal Requirements

The standard: the Web Content Accessibility Guidelines. The current version, WCAG 2.2, is dated as a W3C Recommendation of 12 December 2024, and the W3C notes that “Content that conforms to WCAG 2.2 also conforms to WCAG 2.0 and WCAG 2.1.”
U.S. state and local government, including public schools and universities: the Justice Department’s ADA Title II web rule sets WCAG 2.1 Level AA as the technical standard, with listed exceptions. After an interim final rule published on April 20, 2026, the compliance dates are April 26, 2027 for entities with a total population of 50,000 or more, and April 26, 2028 for smaller entities and special district governments; the education side is covered in education SEO.
Private businesses and other countries: requirements depend on the law that applies to you; if you sell to customers in other jurisdictions, including the European Union, ask counsel which accessibility rules apply to your site.

Testing Both Together

Automated checks (Lighthouse’s accessibility audit, browser extensions, crawlers that flag missing alt text and empty links) find a share of problems quickly.
Manual checks catch problems automated tools can’t detect: navigate with a keyboard only, try a screen reader on key templates, zoom to 200%, read the page with images off.
People with disabilities testing your key journeys find what tools and checklists miss.
Track issues by template, since one template fix repairs every page built on it.

When a crawler report flags images with empty alt text, check each one before filling it in: an image that carries information needs a description of what it shows, while a purely decorative image that isn’t a link should keep alt="" so screen readers skip it.