HTML Tip: Using ALT And TITLE Attributes
Link TITLE Attribute
Image ALT Attribute
The ALT text is meant to provide alternative or substitute text, primarily for use when the image is not being displayed.
Which in itself greatly gives your visitors more information then just a image when mouse is placed over image.
Use this to provide additional information that is not essential. Most visual browsers display title text as a tool tip when the element is hovered over.
One good use of the title attribute is to add descriptive text to links, especially if the link text itself doesn’t clearly describe the link’s destination.