A ribbon is a command bar that organizes the features of a particular program into a sequence of tabs at the top of the program's interface. The purpose behind a ribbon user interface is to allow users to discover and implement more features of a program, learn about the program more quickly and provide users with more control over the program. A common example of a ribbon is the one used in Microsoft Office 2007.
When Microsoft began using a ribbon design as a replacement for menus and toolbars, there arose a concern that outside developers might produce inconsistent ribbon designs. This would result in many Windows applications using different user interfaces, thereby undermining Microsoft's efforts to provide users of their applications with a consistent look and feel. This is why Microsoft issued the guidelines governing the design and use of ribbon user interfaces. While developers are largely free to use Microsoft's ribbon paradigm in their applications as they wish, if it is to be used in conjunction with an application that competes directly with Microsoft products, such as Microsoft Office, a license must be obtained.
The first factor Microsoft asks application developers to consider is whether a ribbon is appropriate for the type of program they are creating. Certain types of programs are more conducive to the ribbon user interface than others. According to Microsoft, ribbons work best for document creation programs, authoring programs, document viewing programs and browsers.
In addition to program types, Microsoft asks developers of ribbon user interfaces to consider whether users of a program face any discoverability or learning issues. If, for example, users are requesting that Microsoft add features to program that have already been implemented, this is a sign that the user interface is poorly designed and that the program could benefit from a ribbon. Microsoft also encourages users to consider whether the program could benefit from a more centralized command structure, and whether the program could benefit from a reduction in the number of commands easily available. In each of these cases, the use of a ribbon would be encouraged.
Microsoft's Ribbon UI guidelines also include information on a number of specific topics including tabs, contextual tabs, modal tabs, standard ribbon tabs, icons, previews, general commands, presentation commands, interaction commands, access keys and keytips, dialog box launchers, application buttons, galleries, standard ribbon groups, labels, documentation, presentation and enhanced tooltips.