Alt Text Isn't Just an SEO Trick
Why alt text exists for accessibility first, what actually makes a description useful to a screen reader, and where keyword-stuffed alt text backfires.
Published March 8, 2026
Alt text gets talked about almost entirely as an SEO tactic, which gets the order backward. It exists so a screen reader can tell a blind or low-vision user what an image shows, since they can't just look at it. Search engines using alt text as a ranking signal is a genuine side effect of that original purpose, not the reason it was invented, and forgetting that order is exactly how alt text ends up stuffed with keywords instead of actually describing anything.
What a screen reader actually does with it
A screen reader announces the alt text out loud (or through a braille display) in place of the image. "Image" with no further description tells a user nothing. A filename like "IMG_4821.jpg" read aloud tells them even less, and it's a surprisingly common finding: images that technically have alt text, but alt text that's just the file's own name, copy-pasted by an image upload tool that never got a real description.
What makes alt text actually useful
Describe what the image conveys in context, not just what's literally in it. A product photo's alt text should mention the product and its relevant visible detail ("navy blue wool sweater, cable-knit pattern"), not a generic "product photo." A chart's alt text should summarize what the chart shows, since a screen reader user can't visually scan axes and trend lines the way a sighted user can.
Keep it reasonably short, a sentence is usually enough, since a screen reader reads the whole thing aloud every time. And skip phrases like "image of" or "picture of", screen readers already announce that it's an image before reading the alt text, so those words are just redundant noise repeated on every single image.
When empty alt text is the correct choice
Purely decorative images, a background flourish, a divider graphic, an icon that's purely visual flair next to text that already says the same thing, should have empty alt text (alt=""), not a description. An empty alt attribute tells a screen reader to skip the image entirely, which is exactly right when there's nothing meaningful to announce. The mistake isn't leaving decorative images with empty alt text, it's leaving meaningful images that way too.