Alt Text
Last updated September 2026
Alt text is a written description added to an image's HTML that describes what the image shows. It serves accessibility, letting screen readers convey image content to visually impaired users, and it helps search engines understand and index images for image search results.
Alt text, short for alternative text, lives in an image's HTML attribute and does two distinct jobs at once. A screen reader reads it aloud in place of an image for a visually impaired user, which makes it a core accessibility requirement rather than a purely SEO one. It also gives search engines, which cannot fully interpret the visual content of an image on their own, a text description to associate with that image for indexing and image search.
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Writing alt text that actually serves both purposes
The strongest alt text describes what is genuinely in the image, specifically enough to be useful to someone who cannot see it, without turning into a list of keywords stuffed in for search engines, the same restraint on-page SEO rewards elsewhere on a page. An image of a therapist in an office should describe that scene plainly; padding the description with unrelated service keywords defeats the accessibility purpose and reads as manipulative to search engines besides.
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Describe the actual content and function of the image, not the page's target keyword list
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Keep it concise, generally under about 125 characters, since that is roughly what most screen readers announce cleanly
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Leave the alt attribute empty, not missing, for purely decorative images that convey no information
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Avoid phrases like "image of" or "picture of"; screen readers already announce that it is an image
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Write unique alt text for each image rather than reusing the same description across a gallery
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The SEO upside beyond accessibility
Well-written alt text helps a page rank in Google Images and gives search engines additional, legitimate context about a page's overall topic. It also becomes the fallback content displayed if an image fails to load, which matters more than it might seem on slower connections or when a hosting issue breaks an image temporarily.
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Where sites most often get this wrong
The two most common failures are opposite problems: leaving alt text blank across an entire site, which fails accessibility standards and forfeits image search visibility entirely, or stuffing every image's alt text with the same repeated keyword phrase, which reads as spam to both users relying on a screen reader and to search engines evaluating content quality. Neither serves the actual purpose of the attribute.
