Alt Text

Alt text (alternative text) is an HTML attribute added to image tags that describes the content and function of an image on a web page. It serves three primary purposes: providing text for screen readers used by visually impaired users, displaying a text placeholder when images fail to load, and helping search engines understand what an image depicts since they cannot interpret visual content the way humans do.

Why It Matters for SEO

Alt text is the primary way search engines understand image content. Well-written alt text helps your images appear in Google Image Search, which accounts for a significant portion of all Google searches. Images with optimized alt text can also improve the topical relevance of the page they appear on, providing additional context about the page content.

Beyond image search, alt text is essential for web accessibility compliance. Sites that follow accessibility standards tend to provide better user experiences overall, which aligns with Google’s emphasis on E-E-A-T and page experience signals.

How to Write Effective Alt Text

Describe the image content specifically and concisely, typically in 5-15 words. Focus on what the image shows and why it is relevant to the page content. Include your target keyword naturally when it genuinely describes the image, but do not force keywords into descriptions where they do not fit.

For product images, include the product name, brand, and distinguishing features. For infographics or charts, summarize the key data point or conclusion. For decorative images that add no informational value (design elements, spacers, borders), use an empty alt attribute (alt="") so screen readers skip them.

Context matters: the same image might need different alt text depending on the page it appears on. A photo of running shoes on a product page needs product-specific alt text, while the same photo on a blog about marathon training needs contextual alt text.

Common Mistakes

• Leaving alt text empty on informational images: Every image that conveys meaning should have descriptive alt text. Empty alt tags on important images are a missed SEO opportunity and accessibility violation.
• Stuffing keywords: Alt text like “buy cheap running shoes best running shoes sale” is spam. Write natural descriptions that serve the user first.
• Starting with “image of” or “picture of”: Screen readers already announce that the element is an image. Jump directly into the description.
• Using file names as alt text: Text like “IMG_4523.jpg” or “hero-banner-v2” provides no useful information to search engines or users.
• Applying the same alt text to multiple images: Each image should have unique alt text that describes its specific content.

Alt text is a small detail with significant cumulative impact on image search visibility, accessibility, and overall on-page SEO.