If you are new to Office 2013, you will notice a new control button joining the familiar help, minimize, maximize and close buttons in the upper right of each Office program. The new button is the Ribbon Display Options button.
The functions of Help (F1 is still the help shortcut key), minimize, maximize/resize and close buttons have not changed and are familiar to all Windows users. Since the ribbon is now the standard interface across all the Office apps, a more obvious, standardized way of controlling the appearance of the ribbon has been introduced. Clicking the Ribbon Display Options button reveals the following choices: Auto-hide Ribbon, Show Tabs, and Show Tabs and Commands.
The last of these is what we are used to seeing in the Office programs, Show Tabs and Commands. In Office 2010 it was possible to double-click one of the familiar tabs, and hide the commands, but not to hide the tabs themselves. Now this functionality has been expanded and moved to a control button.
Auto-hide Ribbon causes the tabs, ribbons and quick access toolbar to completely disappear, giving you the maximum amount of space to edit documents. When the ribbon is needed, simply move the mouse to the top of the screen and click. The ribbon, and quick access toolbar, including ribbon commands, will reappear and remain in place.
Show Tabs now has the same effect as double clicking a tab in Office 2010 did, and still does in Office 2013. It shows only tabs, along with the quick access toolbar, but without their associated ribbon commands. Double clicking a tab when tabs only are visible brings back all the commands beneath the tabs.
Show Tabs and Commands is, as always, the default.
With the advent of multiple devices with very small screens, with or without touch, the new Ribbon options make a lot of sense, thus the new control button.