Alternative text is a text replacement for an image, not a place to repeat keywords. Write what a reader would need to understand the page when the image itself is unavailable.
Decide what the image contributes
- For an informative image, describe the relevant subject or information briefly.
- For a decorative image beside equivalent text, use alt="" so assistive technology can skip it.
- For a linked image, describe the link's purpose when the surrounding text does not already do so.
<img src="chart.webp" alt="Monthly sign-ups rose from 120 in May to 185 in June.">
<img src="paper-texture.webp" alt="">Keep filenames and captions honest
A descriptive filename can help a team manage assets, but it does not replace alt text or a caption. Avoid stuffing filenames, alt attributes, and captions with the same search terms.
Review images in context: if the alternative text repeats a nearby caption without adding anything, shorten it. Accessibility and clear content are the goal; search visibility is not a reason to invent image meaning.