The ribbon can be minimized in order to save  screen space.

 

§ Right-click the ribbon, and then click Minimize the Ribbon.

§ To quickly minimize the ribbon, double-click the name of the active tab. Double-click a tab again to restore the ribbon.

§ To minimize or restore the ribbon via Keyboard shortcut press CTRL+F1.

 

To use the ribbon while it is minimized, click the tab you want to use, and then click the option or command you want to use.