Images must have alternate text

Ensure all informative <img> elements have short, descriptive alternate text and all decorative <img> elements have empty alt attributes (e.g. alt="").

There are three main ways to add alternate text to an image:

• Using an alt attribute i.e. <img alt="drawing of a cat" src="...">
• Using an aria-label i.e. <img aria-label="drawing of a cat" src="...">
• Using an aria-labelledby attribute i.e. <img arialabelledby="someID" src="...">

Alt Text Writing Tips

When writing alt text, keep in mind that its purpose is to relay information to blind users about the image’s contents and purpose - blind users should be able to get as much information from alt text as a sighted user gets from the image itself. Alt text should give the intent, purpose, and meaning of the image.

When writing alt text, it is helpful to keep the following questions in mind:

• Why is the non-text content here?
• What information is it presenting?
• What purpose does it fulfill?
• If I could not use the non-text content, what words would I use to convey the same information or function?

Be sure that all text contained in the attribute is useful. Words like "chart," "image," "diagram," or image file names tend not to be very useful and thus should not be used in alt text.

Decorative Elements

Provide "null" alt attributes (using alt="") for images which do not provide information or do not require alternative text because the image is described in the page content. Some developers will mistakenly leave off the alt attribute altogether on images which they deem do not need alternatives. This is not helpful to assistive technology users because the assistive technology, such as screen reader, will often read the source attribute (i.e., file name) as the alternative text. To tell assistive technology to ignore an image, use a "blank alternative text" attribute: alt="".

Example:

<img src="line.jpg" alt="">