The Phrase “Alt Text” comes up a lot when we talk about web and content accessibility. We’ve got lots of content about Alt Text. But Alt Text is not the terminology used by WCAG. Instead, they use the phrase “Text Alternative”. Let’s take a look at why:
What’s the Difference?
Alt Text is a common ‘short-hand’ term used to reference furnishing text alternatives to on-screen images using the alt attribute, the native HTML attribute for providing images with text alternatives. This attribute is intended to be used to provide the text alternative to the content of the element. If, for example, an image were to be unable to load, the value that’s assigned to its “alt” attribute would be displayed instead. When a device that does not display images, like a screen reader, encounters your element, it will also utilize the Alt Text.
Using the alt attribute is one way to provide screen readers and other assistive devices with a textual alternative. But it’s not the only way and it’s not always the best way. In fact, sometimes it’s better not to use the alt attribute. That’s one reason why the WCAG uses the phrase “Text Alternative” instead of Alt Text.
For example, there are times when the text alternative may be redundant. Imagine a photo with a caption. The caption might be describing exactly what’s going on in the photo. Reading the alt text would mean reading that message twice. In this case, a better technique would be to use an “aria-labelledby” tag to specify the caption as the Text Alternative and not use an Alt attribute at all.
Effectively, all alt texts are textual alternatives, but not all textual alternatives are alt text: there is the text required, and the mechanism for providing that text.
Important Take Aways
Remember, this content is meant to provide users with an equivalency of the image. Text Alternatives should convey the intent of the image (i.e. why did the author provide the image in the first place), and may not always be just a description. Often the text alternative is a summary of the image –why it is present on the page or, when used as a clickable graphic, what happens when the user clicks on that graphic (i.e. the text alternative is also announced as the link text to screen readers).