Alt text is one line of text most visitors never see — yet it matters for two real audiences: people using screen readers who can't see the image at all, and search engines that can't "look" at a picture the way a person does. Writing it well is quick once you know what it's for.
What Alt Text Actually Does
- Accessibility — a screen reader reads the alt text aloud so a blind or low-vision visitor knows what the image shows.
- Fallback display — if an image fails to load, the alt text appears in its place.
- Search engine understanding — search engines use alt text, among other signals, to understand what an image depicts.
Because it serves real people first, the best approach is simply to describe the image accurately — good SEO follows naturally from that, rather than the other way around.
How to Write It
Describe what the image shows and why it's there, in plain language:
| Image | Weak alt text | Better alt text |
|---|---|---|
| Product photo of a blue shirt | "image1.jpg" | "Blue cotton shirt, front view" |
| Chart showing sales growth | "chart" | "Bar chart showing monthly sales growth from January to June" |
| Team photo | "photo" | "Maati Tech team at the 2026 office opening" |
| Icon of a compress tool | "" (decorative, fine to leave empty) | (no alt text needed for purely decorative icons) |
A Few Rules of Thumb
- Be specific but concise — one clear sentence is usually enough.
- Don't repeat "image of" or "picture of" — screen readers already announce it's an image.
- Skip keyword stuffing — writing "compress pdf online free compress pdf tool" instead of a real description helps no one and can look manipulative.
- Leave decorative images empty — a background texture or spacer image doesn't need a description; an empty
alt=""tells screen readers to skip it. - Include text that's part of the image, such as a quote in a graphic, so that information isn't lost to screen reader users.
Alt Text vs Caption vs Title
These three are often confused:
- Alt text — describes the image for accessibility and search engines; usually not visible to sighted visitors.
- Caption — visible text under an image, for all visitors.
- Title attribute — shows as a tooltip on hover; used far less often and not reliably supported by screen readers.
Alt text is the one that matters most consistently across devices and assistive technology.
Writing Alt Text at Scale
For a site with many images — a product catalogue, a photo gallery — writing individual, accurate alt text for each one takes real time, but it's worth doing properly rather than leaving it blank or auto-filling with the file name. A practical approach:
- Batch photos by type (all product front views, all detail shots).
- Write a template per type, then customise the specific details (colour, name, feature).
- Avoid copy-pasting identical alt text across genuinely different images.
Where This Fits Into Broader SEO
Alt text is one small piece of a page's overall technical and content quality. For the full picture of how a page performs technically, our SEO Checker reviews multiple on-page factors together, and what is on-page SEO covers the wider set of elements alt text belongs to.
