What is Alt Text?

Definition

Alt text (alternative text) is a written description added to an image's HTML tag (the alt attribute) that describes what the image shows. It serves two primary purposes: providing context to search engines that cannot "see" images, and making images accessible to visually impaired users who rely on screen readers. When an image fails to load, the alt text is displayed in its place as a fallback.

Alt text is an HTML attribute, not a visible caption. It's written as alt="description here" within the <img> tag. Good alt text describes the image's content and function in the context of the surrounding page. For a product photo, this might be "Red leather crossbody bag with gold chain strap." For a chart, it might be "Bar chart showing monthly revenue growth from $50K to $120K over 2024." The key is conveying the information the image provides to someone who cannot see it.

Why It Matters

Alt text is essential for both SEO and accessibility. Search engines cannot interpret image pixels, they rely entirely on alt text and surrounding context to understand what an image depicts and whether it's relevant to a search query. Well-written alt text helps your pages rank in both regular web search and image search results, which collectively drive significant traffic. Image search alone accounts for roughly 20% of all Google searches.

For accessibility, screen readers read alt text aloud to visually impaired users, making your images meaningful rather than invisible barriers. In many jurisdictions, web accessibility is a legal requirement under laws like the ADA and WCAG guidelines. Beyond compliance, accessible sites serve a broader audience, approximately 2.2 billion people globally have some form of vision impairment. Missing or poor alt text creates a frustrating, exclusionary experience for these users.

How to Measure

Audit your site for missing alt text using browser developer tools (right-click an image → Inspect to check the alt attribute), accessibility checkers like axe or WAVE, or by crawling your site with an audit tool. Key checks include: Does every informational image have alt text? Is the alt text descriptive and relevant, or is it keyword-stuffed? Are decorative images properly marked with empty alt attributes (alt="") so screen readers skip them?

Aim for 100% alt text coverage on meaningful images. Prioritize fixing images on your most-trafficked pages first, as these have the highest impact on both SEO visibility and user experience. Check that alt text length stays under 125 characters (longer descriptions should use the longdesc attribute or a visible caption instead). Review your image search traffic in Google Search Console to identify which images already rank and where alt text improvements could drive additional visibility.

How Racoons.ai Helps

Racoons.ai checks for missing alt text as part of its accessibility and SEO audits, flagging images that lack descriptive alt attributes. Our AI analysis connects alt text issues to their impact on search visibility and accessibility, giving you a prioritized list of images to fix.

Best Practices

Write alt text that describes the image's content and function, not just what it literally shows. Consider the context: the same photo of a person might need different alt text on an "About Us" page ("Sarah Chen, VP of Engineering") versus a blog post about remote work ("Employee working from a home office with dual monitors"). Be specific and concise, "Red Nike Air Max 90 running shoe, side view" is better than "shoe" or "product image."

Avoid keyword stuffing in alt text, search engines can detect and penalize unnatural keyword loading. Instead, incorporate relevant keywords naturally where they fit. Never use alt text like "SEO keyword keyword keyword" or repeat the same phrase across multiple images. For decorative images (visual flourishes, spacer images, background textures), use an empty alt attribute (alt="") rather than omitting it entirely. Omitting the alt attribute entirely is an accessibility error, while alt="" correctly signals that the image is decorative.

Frequently Asked Questions