How do I write good alt text?

Describe what the image shows, specifically and briefly, as if telling someone over the phone: "technician installing solar panels on a Bangkok townhouse roof", not "solar panels" and not a keyword string. If the image is purely decorative, use an empty alt attribute.

Does alt text affect rankings?

It is the primary signal for image search, feeds accessibility, and adds context to the page. It will not rescue weak content, but in visual categories, products, portfolios, food, travel, image search is real traffic, and alt text is its ranking layer.

On-Page SEO

Alt Text

Alt text is the written description of an image in a page's HTML, read by screen readers and used by search engines to understand the image.

It improves accessibility and can help images rank in image search. For example, "barista pouring latte art in a Bangkok cafe" is useful, while "IMG_2024" is not. Describe the image naturally rather than stuffing keywords.

Write it as a description of the image for someone who cannot see it, and the SEO takes care of itself. The failure modes are stuffing keywords into it, describing every decorative flourish, and leaving CMS defaults like filenames in place. Decorative images should carry empty alt attributes so screen readers skip them. For pages where images carry the argument, product shots, portfolio work, diagrams, alt text plus descriptive filenames is a genuine image-search channel, and image search is a meaningful discovery path in visual categories.

Example

A cafe uploads a photo as IMG_4382.jpg with no alt text. A screen reader announces "image", and image search sees nothing. Renamed with alt text "barista pouring latte art at a specialty cafe in Thonglor", the photo starts appearing for Thonglor cafe searches, and a blind visitor hears what the picture actually shows. Same photo, one line of HTML apart.

Frequently asked questions

How do I write good alt text?: Describe what the image shows, specifically and briefly, as if telling someone over the phone: "technician installing solar panels on a Bangkok townhouse roof", not "solar panels" and not a keyword string. If the image is purely decorative, use an empty alt attribute.
Does alt text affect rankings?: It is the primary signal for image search, feeds accessibility, and adds context to the page. It will not rescue weak content, but in visual categories, products, portfolios, food, travel, image search is real traffic, and alt text is its ranking layer.

Working on Alt Text? See how our SEO audit can help.

Explore SEO audit

Back to glossary

Alt Text

Frequently asked questions

Related terms