what is alt text? the one line that serves readers, crawlers and google images at once

seo · Mar 18, 2026 · 5 min read

alt text is the written description of an image, living in the html alt attribute. it exists for one audience and accidentally serves three: screen-reader users hear it, search engines read it, and every visitor sees it in the image's place whenever the image fails to load. one line, three jobs.

why it exists — accessibility first

a blind visitor browsing your site hears images announced as "image" — or worse, nothing — unless the image carries a description. alt text is how a product photo becomes "barista pouring latte art at the counter of a small cafe". this is not a nice-to-have: it is the difference between a site a person can use and one they bounce from, and it is the accessibility argument made concrete in what makes a website look trustworthy — care shows in the details nobody was forced to handle.

the seo dividend, honestly stated

because search engines cannot look at pixels, your description is what they know. it feeds google images — a real, underestimated traffic source for restaurants, salons, portfolio work, products — and it helps the page itself: images described in the page's own vocabulary reinforce what the page is about. the finding path is the same one in how do i get my website on google: give the crawler something true to read.

how to write it without overthinking

• describe the image, in plain language, as if on the phone. "wedding cake with three tiers and white peonies" beats "cake img final v2" and also beats a paragraph.

• drop the "image of" prefix. the screen reader already says "image". spend the characters on the description.

• use the page's words where true. if the page is about gluten-free catering and the photo shows the buffet, "gluten-free catering buffet" is honest and aligned — not keyword stuffing, which is the failure mode described in what is keyword stuffing.

• decorative images get empty alt. alt="" is a valid, correct choice: it tells screen readers "skip this, it carries no information". the divider swoosh and the background texture want nothing else. empty is not missing; a stuffed decorative image is worse than silence.

  the five-minute audit

open your site, right-click any image, inspect, look for the alt= attribute. do it for the images on your most important page. three outcomes: a real description — done; alt="" on a genuinely decorative image — correct; no attribute at all — that is the fix list. most small sites are mostly the third one.

FAQ: the questions i actually get

does alt text affect my google ranking?

the page ranking effect is small and indirect; the google images effect is direct and real. if your business sells anything visible — food, hair, rooms, craft — image search is a front door, and alt text is how it opens.

how long should alt text be?

a sentence, roughly. screen readers cut off around 125 characters in some tools, so front-load the description — the same front-loading instinct as writing meta descriptions in how do i write meta descriptions.

what about images with text in them, like infographics?

the alt carries the point of the graphic, not a transcription of every label. if the detail matters, the text belongs on the page; the alt says what the graphic shows at a glance.