Alternative Text for Images

Alternative text (commonly known as alt text) describes visual elements on a webpage or document. Describing images with alt text gives context for people using screen readers so they can access that content.

Tip: As a best practice, alt text descriptions should be 120 characters or less.

In addition to images, alt text is also used to describe images that are within the following content formats:

• Documents
• PDFs.
• Tables
• Infographics

1. Don't use "photo/image of" — Because screen readers and other assistive devices already describe images as such, you don't need to preface alt text with "Image of" or "photo of."
2. Use simple, descriptive language when writing alt text to give the reader a clear idea of what the image depicts.
   1. Close your eyes and think of the image and include information that you'd use to describe it.
3. Keep it relevant — Limit the alt text description to relevant information; you don't have to include every single nuance of an image, just the main details of it.
   1. Consider the purpose of the image on the page. Include the relevant information it's being used to convey.
4. Be concise — A phrase or sentence is usually sufficient.
   1. Note that some screen readers have character limits for alt text descriptions and will stop reading beyond those limits.

• W3C guide to images
• WebAIM guide to alternative text (WebAIM)
• Microsoft Guide to Alt Text