What Is Alt Text?
Quick Definition
Alt text (alternative text) is a written description added to an image's HTML code that describes the image's content and function for screen readers and search engines.
Alt text serves two critical purposes: web accessibility and SEO. For visually impaired users who rely on screen readers, alt text provides a verbal description of images they cannot see. For search engines that cannot "see" images either, alt text explains what an image depicts, helping it appear in image search results.
Writing good alt text is both an art and a science. It should be descriptive but concise (typically 125 characters or less), include relevant keywords naturally (not stuffed), and accurately describe what the image shows. Decorative images that don't convey information can have empty alt attributes (alt="") so screen readers skip them.
Alt text is also what displays when an image fails to load, giving users context about what they're missing. This fallback function makes it important for user experience even beyond accessibility and SEO.
For e-commerce sites, product image alt text is especially valuable — it helps product images appear in Google Image Search, which drives significant shopping traffic. Descriptive, keyword-rich alt text on product photos can be a meaningful source of organic traffic.
Why It Matters
Alt text is one of the easiest SEO wins most websites overlook. Google Images drives billions of searches daily, and proper alt text is the primary way to get your images found. Beyond SEO, alt text is a legal accessibility requirement in many jurisdictions — websites that don't provide it may violate ADA compliance standards.
For content-heavy sites, adding descriptive alt text to every image creates hundreds of additional ranking opportunities without creating new content.
Real-World Examples
A food blog added descriptive alt text to 500 recipe photos and saw Google Images traffic increase by 40% within two months
An e-commerce store wrote unique alt text for 2,000 product images instead of using file names, leading to a 15% increase in organic product page visits
A real estate agency described each property photo with location, features, and room type, capturing searches like 'modern kitchen in Austin TX'
A nonprofit improved their website's WCAG compliance score from 62% to 94% simply by adding proper alt text to all images
Related Terms
On-Page SEO
On-page SEO involves optimizing individual web pages, including their content, HTML source code, and internal links, to rank higher in search engines and earn more relevant traffic.
Technical SEO
Technical SEO refers to the process of optimizing your website's infrastructure so search engines can crawl, index, and render your pages efficiently.
SERP (Search Engine Results Page)
A SERP is the page displayed by a search engine in response to a query, showing organic results, paid ads, featured snippets, and other specialized content.
Meta Tags
Meta tags are snippets of HTML code that provide search engines and browsers with structured information about a web page's content, purpose, and display preferences.
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