When you log out in the standard way, you must close all the documents you are using and quit all of your running applications. It can be inconvenient if another user needs to use the computer.

You can use “fast user switching” to allow more than one user to stay logged in to a computer at a time.

When fast user switching is turned on, the current user’s name appears in the upper-right corner of the menu bar. You can then choose another account from the menu.

The big advantage is that the previous account is still logged in and all the applications and documents can remain open. When the time comes to log in to the previous account, you can choose the account name from the menu and you switch back to the previous account.