Definition - What does Alternate Text (Alt Text) mean?
Alternate text (Alt text) is a text description that can be added to an image's HTML tag on a Web page. It is used when the image in the Web page cannot be displayed, in which case the Alt text is shown instead. It is also displayed when a user mouses over the image. Alt text is one of the important attributes required by the image tag. Proper implementation of Alt text can help increase Web accessibility. Alt text is also very important for search engines, which cannot determine the content of images, and must rely on Alt text to determine their contents.
Techopedia explains Alternate Text (Alt Text)
Alt text can be represented in two ways:
Within the image element’s alt attribute
In the surroundings or in the context of the image
The functions of Alt text are:
It's easily read by screen readers in place of images. This allows the content to be accessed by visually impaired people or people with other cognitive disabilities.
It is placed instead of the image in browsers that cannot support the image display or are not set to view images
It applies a description and semantic meaning to images. This can easily be read by search engines and is used to determine the content of an image.
The following reccomendations apply to using Alt text :
For decorative images, Alt text should be kept blank.
For images containing text, Alt text needs to replicate the full text.
For graphs and charts, Alt text needs to summarize the trend depicted.