Definition
Text alternative (alt text)
The textual description of an image, read by assistive technologies when the image cannot be seen.
Text alternative (the alt attribute) describes the content or function of an image. It lets people who cannot see the image understand the information it conveys.
A purely decorative image gets an empty alternative, so the screen reader ignores it. An informative image gets a concise, relevant description.
Frequently asked questions
How long should a text alternative be?
Short enough to be read in one go, precise enough to replace the image: one sentence is usually enough. What matters is the information the image carries, not a character count.
Does every image need a text alternative?
No. A purely decorative image should carry an empty alt attribute so screen readers skip it. An image that carries information must be described.
See also
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