Alt text
Also known as: alt attribute, alternative text, image alt tag
Alt text is a short written description added to an image with the HTML alt attribute. Screen readers read it aloud for people who cannot see the image, browsers show it when an image fails to load, and search engines use it to understand and rank images.
- Set with the alt attribute on an <img> tag
- Read by screen readers and shown when images fail to load
- Use empty alt ("") for purely decorative images
Why alt text matters
Alt text serves accessibility first: a screen reader announces the alt attribute so a blind or low-vision user knows what the image shows. It is also a fallback — if an image fails to load, the browser displays the alt text in its place.
For SEO, alt text gives search engines context they cannot get from the pixels alone, which helps the image rank in image search and reinforces the topic of the page.
Writing good alt text
Describe the image clearly and concisely, conveying its meaning rather than listing every detail. Skip phrases like "image of" — screen readers already announce that it is an image.
Decorative images that add no information should use empty alt text (`alt=""`) so screen readers skip them. Avoid keyword stuffing; an accurate description serves both users and search engines.