Alt text

Alt text, defined

Alt text, from the HTML alt attribute, is a short written description of an image. Screen readers read it aloud to people who can't see the image, and browsers show it if the image fails to load. Google uses it, along with surrounding text, to understand images. Its image SEO best practices recommend useful, descriptive alt text rather than stuffing keywords.

An example from a UK business

A bakery's product photos all have alt text "IMG_4021". It rewrites them as "Three-tier lemon and elderflower wedding cake with fresh flowers". Screen reader users now know what's pictured, and the image can appear for people searching for elderflower wedding cakes.

What to avoid

• Leaving camera file names as alt text.
• Stuffing keywords into every description.
• Writing "image of" or "picture of" at the start, which screen readers make redundant.
• Describing decorative images that add nothing.

A quick check you can do now

Free accessibility checkers and SEO crawlers list images missing alt text. You can also right-click an image, choose "Inspect" and look for the alt attribute. Purely decorative images, such as background patterns, should have empty alt text (alt="") so screen readers skip them.

What it changes for you

Alt text is accessibility first. It makes your site usable for more people and helps you meet good practice under equality law. It also helps your images appear in Google Images for relevant searches, which matters for visual businesses such as builders, salons and landscapers.

It's also one of the easiest jobs to keep up with as you go. Writing a sentence of alt text when you upload a photo takes seconds, while fixing hundreds of images later takes hours.

Other on-page terms

• Image SEO: Filenames, alt text, compression and placement for images.
• UX and SEO: Overlap where usability, speed and clarity support search performance.