Alt text and images
Alt text describes an image well enough that someone who cannot see it knows exactly what is there.
You write alt text for images as a short, factual description of what can be seen in the image, so a screen reader and a search engine both understand what is there.
Alt text describes what is literally visible, in plain language and without forcing a keyword into it. Google uses that text to connect images to searches in Google Images and to get context for the rest of the page. A screen reader reads the same text aloud, so sloppy or empty alt text hits two audiences at once.
How to write good alt text
- Describe what is literally visible. Name the subject, the action and relevant details, such as “trainer running a workshop for a group of ten participants”, instead of a vague summary.
- Keep it short. A sentence of ten to fifteen words is usually enough, and anything longer rarely gets read out in full by a screen reader.
- Leave decorative images empty. A purely decorative element, such as a divider or a background pattern, needs no alt text, because a description there would only distract.
Why images do more than decorate
- They pull in their own traffic. Google Images is a separate source of visitors, with its own search behaviour and its own opportunities apart from the ordinary results.
- File name and compression count. A descriptive file name and a compressed format help both speed and findability, see Core Web Vitals explained for the effect on loading time.
- Accessibility is no side issue. Good alt text makes your site usable for people who rely on a screen reader, which is reason enough to take it seriously even apart from SEO.
For the definition of alt text itself, read wat is alt-tekst.
Want to see which images on your site still have no alt text? Take the free AI-zichtbaarheidscheck.
Frequently asked questions
Does every image need alt text?
Every image that adds something to the content does. Purely decorative elements can be left with empty alt text.
May I put a keyword in the alt text?
Only when it fits the description naturally. Alt text consisting of stacked keywords works against you and helps nobody who cannot see the image.
Does alt text count for ordinary search results too?
To a limited degree. It adds to the context of the whole page, though it weighs far less heavily than the running text itself.
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