It is important that hyperlinks are accessible to make them recognizable by users of keyboard and assistive technology. Therefore, it is necessary to add an alternative text to make sure that screen readers are able to read it out loud instead of reading a hyperlink.
In the image below, a screen reader would only be able to read the hyperlink for the user.
Thus, it is important to add an alternative text to enable the screen reader to read a description of the certain hyperlink. Here is an example:
When writing alternative text, strive to be informative, not poetic, and remember that brief is better. Use complete sentences with proper punctuation and check your spelling. Do not include any information that is already present in the caption.