Like most programs, all commands and tools available in the tabs on the ribbon have shortcut keys for faster access. You can also easily view available shortcut keys (including keys for commands on the active tab), to help in learning the shortcuts more quickly.
To view and use shortcut keys:
Press Alt. The shortcut keys are displayed over each command available from the current view.
Press the letter that corresponds to the command you wish to use
Depending on the key you press, you may be presented with additional shortcut keys. For example, pressing R displays the Review tab, along with the shortcut keys for the reviewing tools.