alt text

Short for alternative text. It is represented in HTML by the alt attribute.

alt text (countable and uncountable, plural alt texts)

 

English Wikipedia has an article on:

alt text

Wikipedia

1. (Internet) A text caption, associated with an image or other element, that is rendered if the usual content cannot be rendered.

   Screenreaders for the blind read out the alt text when they encounter an image on a Web page.

• parallel text