What is alt text?
Alt text, or alternative text, is a short description added to an image's HTML so that screen readers and search engines can understand it. It also appears in place of the image if the file fails to load.
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Why alt text matters
People who use screen readers rely on alt text to know what an image shows. Without it, they may hear nothing, or only a file name.
Search engines also read alt text to understand what an image is about. That helps your images appear in image search and gives extra context for the page around them.
How to write good alt text
Describe the image the way you would to someone who can't see it. Keep it short and specific, and mention a keyword only when it fits naturally.
Skip phrases like "image of" because screen readers already announce an image. Decorative images that add no information can use an empty alt attribute so they are skipped.
Common questions
Is alt text a ranking factor?
Alt text helps search engines understand an image, which can support image search visibility. It's one small signal among many, so write it for people first.
How long should alt text be?
Keep it as short as you can while still describing the image. A short phrase or a single sentence is usually enough.
Does every image need alt text?
Every image should have an alt attribute. Meaningful images need a real description, while purely decorative ones should have an empty attribute so assistive tools skip them.
What is the difference between alt text and a title attribute?
Alt text describes the image for screen readers and search engines, and it shows if the image can't load. A title attribute is optional hover text and isn't a reliable replacement for alt text.
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