Using alt attributes on img elements

Important Information about Techniques

See Understanding Techniques for WCAG Success Criteria for important information about the usage of these informative techniques and how they relate to the normative WCAG 2.1 success criteria. The Applicability section explains the scope of the technique, and the presence of techniques for a specific technology does not imply that the technology can be used in all situations to create content that meets WCAG 2.1.

Applicability

Images used within HTML documents.

This technique relates to Success Criterion 1.1.1: Non-text Content (Sufficient).

Description

When using the img element, specify a short text alternative with the alt attribute. Note. The value of this attribute is referred to as "alt text".

When an image contains words that are important to understanding the content, the alt text should include those words. This will allow the alt text to play the same function on the page as the image. Note that it does not necessarily describe the visual characteristics of the image itself but must convey the same meaning as the image.

Examples

Example 1

An image on a Website provides a link to a free newsletter. The image contains the text "Free newsletter. Get free recipes, news, and more. Learn more." The alt text matches the text in the image.

<img src="newsletter.gif" alt="Free newsletter. 
   Get free recipes, news, and more. Learn more." />

Example 2

An image on a Web site depicts the floor plan of a building. The image is an image map with each room an interactive map area. The alt text is "The building's floor plan. Select a room for more information about the purpose or content of the room." The instruction to "select a room" indicates that the image is interactive.

Resources

Resources are for information purposes only, no endorsement implied.

HTML 4.01 IMG element

HTML 4.01 alt attribute

Tests

Procedure

  1. Examine each img element in the content
  2. Check that each img element which conveys meaning contains an alt attribute.
  3. If the image contains words that are important to understanding the content, the words are included in the text alternative.

Expected Results

Checks #2 and #3 are true.