Alt text (alternative text) is a written description of an image in HTML (alt="..."). Screen readers announce it to people who can’t see the image, and browsers show it if the file fails to load.

Good alt text describes the meaningful content or function of the image — not “image123.jpg” or a dump of keywords. Decorative images can use empty alt (alt="") so assistive tech skips them. It’s a core accessibility practice and a small SEO bonus when the description is accurate.

A real-life example of alt text

A product photo of white leather sneakers. Weak: “shoes.” Better: “white leather sneakers with gum sole, side view.” A screen-reader user understands the product; search engines get context too.

Alt text won’t fix a confusing layout, but missing it locks people out. Pair it with contrast, labels, and keyboard access. See Web Accessibility and Inclusive Design and image tips in Beyond Add to Cart.