编写传达用途而非像素的替代文本

Good alt text describes what an image means in context, not a pixel-by-pixel account of every color and shape.

Ask why the image is here. The answer is its purpose, and your alt text should deliver exactly that, nothing more.

Do not start with image of or photo of. Screen readers already announce it is an image, so those words just waste time.

Aim for a short, complete phrase, usually under about 125 characters. If you need more, the image may be complex.

The same dog photo might be a breed example or a happy-customer story. Let the surrounding context shape your words.

When an image is the only thing inside a link, its alt must describe the link destination, not just the picture.

If a graphic contains words, your alt text must include all of that text so nothing is lost to non-sighted users.

If a caption right next to the image already says it, an empty alt avoids making screen readers hear it twice.

Imagine reading your alt text aloud to someone on the phone. If they get the same point, you achieved true equivalence.

Alt text is not an SEO dumping ground. Cramming in keywords hurts real users and is exactly what good alt avoids.

End alt text with a period. That small punctuation gives the screen reader a natural pause before moving on.

Pick the strongest alt text below.

Great progress! Strong alt text captures purpose in a tight phrase, skips image of, respects context, and never stuffs keywords.