Image alt text: what it's for, and how to get it right

Do alt tags matter for SEO?

Yes — with honest caveats. Alt text is how search engines understand image content, it's a ranking factor for image search, and it adds context to the page it sits on. But it is a modest page-ranking signal: good alt text won't rescue weak content, and its first job was never SEO at all.

The first job is accessibility. Screen readers speak the alt text aloud to people who can't see the image; it's also what renders when an image fails to load. Write for that reader and the SEO value follows for free — which is the pattern with most on-page work.

What good alt text looks like

Describe what the image shows, in the context of the page, the way you'd tell a colleague on the phone:

• Weak: alt="image1", alt="photo" — says nothing.
• Spam: alt="rank tracker cheap rank tracking SEO tool best" — written for a robot from 2009, and the robot has moved on.
• Good: alt="Line chart of a keyword climbing from position 18 to 2 over six weeks" — a person who can't see the chart now knows what it shows.

Practical rules that cover almost every case:

• Be specific and brief — usually one sentence, rarely more than ~125 characters.
• Skip “image of” / “picture of”; the screen reader already announces it's an image.
• Mention a keyword only when it genuinely describes the image. Never force it.
• For functional images (a logo that links home, an icon button), describe the function: alt="PicoRank home".

When empty alt is correct

Purely decorative images — background flourishes, spacers, ornamental icons next to visible text — should carry an empty alt attribute: alt="". That tells screen readers to skip them instead of reading a filename aloud. Empty alt is a deliberate choice; a missing alt attribute is a bug. Audits (ours included) distinguish the two.

Fixing a whole site without losing a week

1. Inventory first. Crawl the site and list every image with a missing alt attribute — you want counts per template, not a page-by-page safari.
2. Fix by template, not by page. Most missing alts come from a handful of components: the blog cover image, the product thumbnail, the team photo block. One template fix can clear hundreds of findings.
3. Sort content images by traffic. For hand-written alts, start with the pages people actually visit.
4. Mark the decorative ones empty as you go, so they stop showing up in every future audit.

Then re-crawl and watch the count drop. (PicoRank's audit tracks each finding across runs, so the before/after is explicit rather than vibes.)