Tooltip
Alternatively
referred to as a ScreenTip, a Tooltip is a tip given about an object when the mouse cursor is placed over it. Tooltips are helpful for new
users because they enable the user to learn about each icon or object
by hovering their mouse over them.
In the picture to the right, is an example of a Tooltip in Microsoft Word
describing the formatting marks button as showing marks or hiding the marks.
Also see: AutoText, Balloon, Cursor, Hover, Operating System definitions