Alt Text
Also called Alternative text, Alt attribute, Image alt text.
Alt text is a written description added to an image's HTML alt attribute that communicates image content to search engines, screen readers, and browsers when images fail to load.
What it means
Alt text is the text inside an image's `alt` attribute — `<img src='seo-checklist.webp' alt='Technical SEO checklist showing 12 crawlability audit steps'>`. It serves three purposes simultaneously: it tells screen readers what the image depicts (essential for accessibility), it displays as fallback text when an image fails to load, and it gives search engines a text description of the image's subject — enabling both the page and image to appear in image search.
Good alt text is descriptive and specific. Bad alt text is either missing, generic ('photo', 'image1.jpg'), or keyword-stuffed ('SEO agency best SEO services SEO results'). The best alt text describes exactly what the image shows in natural language, including contextually relevant terms where they fit without forcing them. A screenshot of a Google Search Console crawl error report doesn't need 'SEO agency' in the alt text — describing what the screenshot actually displays is both more honest and more useful.
Alt text also functions as an on-page topical signal. Images with descriptive alt text that aligns with the page's topic reinforce relevance to that topic. Images used as links (icon buttons, linked images) should carry alt text that describes the destination or action — functioning the same way anchor text does on a text link — rather than describing the visual appearance of the image itself.
Key takeaways
- Every meaningful image needs descriptive, specific alt text — missing alt text is both an SEO and accessibility issue
- Keyword-stuffed alt text is a spam signal that harms both SEO and usability
- Decorative images (visual dividers, abstract backgrounds) should use empty alt (alt='') so screen readers skip them
- Images used as links need alt text describing the destination, not the image appearance
- Alternative text
- Alt attribute
- Image alt text
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