All images -- including transparent GIFs -- must have "alt" text (short for "alternate"). Alternate text describes the information in the image, which is useful for three important purposes:
Some user agents render the alt text as a tool-tip: the little yellow box that pops up when you hold your mouse cursor over the image.
Alternate text should be concise (i.e. 10-12 words maximum containing no more than 150 characters including spaces and punctuation). For transparent images and spacers, use alt="" (NULL), alt=" " (spaces are acceptable), or alt="blank". Any words depicted in the image should also appear in the "alt" text description.
![]() | <img src="banana.jpg"> |
![]() | <img src="banana.jpg" alt="A picture of a banana."> |
Add a concise (no more than 150 characters) description of the image as an alt attribute.