Alt Text

The descriptive text defined in an image’s HTML alt attribute; essential for accessibility and critical for image SEO and screen readers.

Alt Text (Alternative Text / Alt Text) is the text defined in the alt="" attribute of an HTML image that describes what the image is about. It has three core functions:

• Accessibility: Screen readers read alt text aloud to visually impaired users. It is a core requirement of the WCAG accessibility standard.
• SEO: Search engines understand the image’s content from alt text; it is a primary signal for ranking in Google Images.
• Fallback display: If the image cannot load, the browser shows the alt text in place of the image.

Characteristics of good alt text:

• Clearly describes the image (“red running shoe side view”)
• Is written naturally, without keyword stuffing
• Does not exceed 120 characters
• Is left empty for decorative images (alt="")
• Does not begin with the words “image” or “photo” (unnecessary)

Tip: On image-heavy pages, auditing alt text can improve both accessibility and traffic from Google Images.