What is alt text and why does it matter?
Alt text isn't just an accessibility checkbox. Here's what it actually is, who it helps, and how to write it well.
Alt text is invisible. That’s the point.
Alt text — short for alternative text — is a written description attached to an image on the web. It lives in the alt attribute of an <img> tag, and most of the time, you never see it.
That’s by design. Alt text isn’t for you — or at least, it’s not only for you.
Who it’s actually for
Screen readers read alt text aloud for users who are blind or have low vision. Search engines index it to understand what an image contains. It renders in place of broken images. It reaches anyone browsing with images disabled, on a slow connection, or using an assistive device you’ve never thought about.
When alt text is missing — or lazy (“image.jpg”, “photo”, “untitled”) — all of those people hit a wall. Not a dramatic one. Just a quiet dead end where meaning was supposed to be.
What good alt text actually looks like
Good alt text is specific and functional. It describes what’s in the image in the context of the surrounding content — not in isolation. A few principles that hold up:
- Don’t start with “image of” or “photo of” — screen readers already announce that it’s an image. You’re doubling up on information nobody needs.
- Be specific. “Golden retriever catching a frisbee in a park” does more than “dog outside.”
- Match the context. A product photo on an e-commerce page needs different alt text than the same photo in a long-form article.
- Decorative images get empty alt text. If an image is purely visual — a divider, a background texture, pure aesthetic — use alt="" and let screen readers skip it entirely.
None of this is complicated. But it does require stopping for a second.
Why that second keeps getting skipped
Writing alt text takes a moment. That moment gets dropped constantly — when you’re publishing fast, when your CMS doesn’t surface the field prominently, when images were uploaded by someone else months ago and nobody went back. The result is millions of images with missing, placeholder, or misleading alt text across the web. Not because people don’t care. Because the workflow doesn’t make it easy to care.
A note on tools
There are browser extensions now that can generate alt text for images on any page — right-click, get a description, copy it where it needs to go. They’re not a replacement for judgment (context still matters and you still own the final copy), but they make the blank field a lot harder to ignore.
The principles above still apply either way. The tool doesn’t know your context. You do.