Image SEO: Why Alt Text Matters

Photographs make website content more engaging. People often find pages with useful images more interesting to read than text alone.

Good alt text also helps search engines understand and index your website's images.

The term ‘alt tag’ is commonly used for an image's written description, although it is technically an HTML attribute. It should describe what the image shows. Search engine crawlers and screen readers use this text to interpret the image.

What is an alt attribute?

It is part of an HTML image element, for example:

<img src="image.jpg" alt="image description" title="image tooltip">

Beyond search engine optimisation, alt text helps people who cannot see the image understand the information it conveys.

Alt text as an SEO consideration

Google's image guidance explains the value of providing image information in text as well as visually. A useful description gives search engines more context and may naturally include relevant keywords (see our guide to keyword research).

Choose descriptive wording rather than filling the attribute with keywords. The text should match what the image shows; keyword stuffing may be treated as spam.

An image's filename should also reflect its content as clearly as possible.