In Microsoft Office 2007 and 2010 applications, like Word, Excel, PowerPoint, and Outlook, a keytip is a keyboard shortcut to use a function on a ribbon, also called a ribbon control. There are multiple and varied ribbons in an Office application; however, the Home ribbon is found in most of them. This ribbon contains some of the more common controls utilized by Office users, as seen in the image below.
A ribbon contains unique keytips for each ribbon control, but a single keytip could be shared between ribbons. Keytips are activated by pressing the Alt key plus the keyboard shortcut, the keytip, associated with the ribbon control.