The ribbon is a graphical user interface widget composed of a strip across the top of the window that exposes all functions the program can perform in a single place, with additional ribbons appearing based on the context of the data.
One of the main driving ideas behind using a ribbon is enhancing usability; by consolidating the program's functions and commands in an easily recognizable place, one need not look through multiple levels of hierarchical menus, toolbars or task panes before finding the right command.