A short written description of an image, added in the page code. Screen readers read it aloud, and Google uses it, with the page text, to understand the image.
Example
For a photo of a blue block-print kurta, Meera writes alt text 'Indigo block-print cotton kurta, straight cut, three-quarter sleeves', not 'IMG_2041' or a string of keywords.
How you'll hear it
“Half the product images have no alt text, so we are invisible in image search and unreadable for screen readers.”
Don't confuse it with
- Image file name: also helps a little, but alt text is the description Google and screen readers rely on.
- Caption: visible text under an image; alt text is usually not shown.
Related terms
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Sources
- Google image SEO best practices, Google Search Central
- SEO Starter Guide, Google Search Central