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alt tags

GUIDELINES 1.1

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Overview

Alt tags serve as text descriptions for images, assisting screen reader users and those with vision impairments in understanding image content. They are important for accessibility and help when images fail to load.

Who is impacted

Users who are blind or have low vision and rely on screen readers to interpret image content.

How to test

Inspect images in your HTML and verify each has a meaningful alt attribute. Use a screen reader to confirm descriptions are read aloud.

Resources

Visit W3C WAI Images Tutorial and WebAIM Alternative Text guide for detailed guidance.

What are Alt Tags?

Alt tags, also known as alt attributes or alt text, are text descriptions applied to images in HTML. They serve as a textual alternative when images cannot be displayed or perceived by users. Screen readers read alt text aloud to visually impaired users, making it a critical component of web accessibility.

Every meaningful image on your website should have descriptive alt text that conveys the purpose and content of the image. Decorative images that do not add information should have empty alt attributes (alt="") so screen readers skip them.

How to Write Good Alt Text

Good alt text is concise, descriptive, and contextual. Describe what the image shows and why it matters in the context of the page. Avoid starting with "image of" or "picture of" as screen readers already announce it as an image. Keep descriptions under 125 characters when possible, and use longdesc or figure captions for complex images like charts or infographics.