Alt text vs. captions vs. descriptions: what's the difference

You upload a product photo and three fields stare back at you: alt text, caption, maybe a "description" field too, depending on the platform or CMS. Most people write one good sentence and paste it into all three. It feels thorough. It's actually a missed chance — each field has a different job, and a different audience.

Three fields, three jobs

Alt text describes the image for someone who can't see it — a screen reader reads it aloud, and it's never visible on the page itself. It should be plain and literal: what's in the picture, nothing more.

A caption is visible copy that sits next to or under the image, and everyone reads it, sighted or not. It can do things alt text can't: crack a joke, name a person who isn't identifiable from the photo alone, link to a product, or push a call to action.

An image description — sometimes a separate "long description" field for infographics, charts, or diagrams — exists for images too complex for a single sentence of alt text. It carries the data or structure a chart contains, in a format a screen reader can read start to finish.

Why teams collapse them into one

Under deadline, writing three versions of the same idea feels redundant, so the caption — hashtags, tags, and all — gets copied straight into the alt text field. The result: alt text that reads like a caption, and doesn't actually describe the image for someone who needs that description.

Notice the strong version says nothing about "new drop" or stock status — that information belongs in the caption, where a sighted reader and a screen reader user both see it as regular page content. The alt text's only job is the boot itself.

A fast way to check you got it right

Read your alt text out loud, alone, with no other context. If it sounds like a tweet — emoji, a call to action, a brand voice bit — it's doing the caption's job. If your caption reads like an inventory listing with no personality, it's doing alt text's job instead. Swap what needs swapping, and let each field carry only the weight it was built for.