alt

This attribute defines the alternative text describing the image. Users will see this displayed if the image URL is wrong, the image is not in one of the supported formats, or until the image is downloaded.

Usage note: 
Omitting this attribute indicates that the image is a key part of the content, but no textual equivalent is available. Setting this attribute to the empty string indicates that this image is not a key part of the content; non-visual browsers may omit it from rendering.
