Image alt text: the description written for people who cannot see the image

Alt text is written twice, for the visitor who cannot see the image and for the engine that cannot either, and both read the same honest sentence.

Alt text is the least visible writing on a website, which is exactly why it gets skipped. It sits behind the image, unseen by most visitors, until the day it is the only thing there: the screen reader reading the page aloud, the broken-image icon where a photo should be, the search engine cataloguing a picture it cannot look at. A site can look finished with every alt field empty. It is finished the way a book is finished with blank pages in the middle.

The honest framing: alt text is written twice over. Once for the visitor who cannot see the image, and once for the engine that cannot see it either, and both read the same sentence. That shared sentence is why the honest description beats the keyword-stuffed one: a string of search terms reads as noise to the person relying on it, and engines have read enough alt text to tell a description written about the picture from one written at the picture. The same sentence serves both, or it serves neither well.

The failures repeat across the web. The empty field on the one photo that carries the page's whole point, so the page says everything except what it exists to say. The filename pasted in as the description, which describes nothing to anyone. And the keyword list, six product names in a row, which reads to the visitor who needs it most like exactly what it is: text written for a machine, dumped where a human was standing.

The practice is plain writing under pressure. Describe what the image shows and why it is there, in language a colleague would use, and keep it brief: a sentence does the work where a paragraph would drown the page. Say chart, say diagram, say the thing the picture proves. And if the image is decorative, leave the alt out entirely and let the reader pass without a speed bump, because describing a divider line is a courtesy nobody asked for.

Then check alt text wherever the images actually come from. A site template may ship defaults you never chose. A stock photo arrives with no context at all, and a description copied from the stock library describes a stranger's context, not yours, so it helps nobody. Your own product photos, your own team, your own screenshots deserve descriptions written by someone who knows why the image is on the page. The publishing system makes this a field; only you can make it a sentence.

We build every site we ship with this field treated as content rather than an afterthought, and our own pages pass the test we describe: no meaningful image goes out undescribed. Guidance, not guarantees: formal accessibility conformance, jurisdiction-specific requirements, and how any particular engine weighs alt text belong to accessibility specialists and the standards bodies themselves. Write the honest sentence, keep it brief, and let it do both jobs at once.