What macOS feature allows fast switching between user accounts without logging out?

Fast User Switching allows Mac users to switch between accounts without logging out or quitting the applications in another user’s session. Each person can keep a separate desktop and set of running apps active, making the feature useful on shared household or workplace Macs.

When enabled, the current user can select another account from the macOS menu bar or login interface. The second user authenticates with a password, Touch ID, or another available method, while the first user’s session remains suspended in the background. Returning to it restores the previous desktop and open applications.

Fast User Switching is different from the Login Window. The Login Window is where a user signs in, while Fast User Switching is the mechanism for moving between active sessions. It is also not the same as Guest User, which creates a temporary restricted session. Apple introduced the feature with Mac OS X Panther in 2003, making multi-user sharing more practical without forcing repeated logouts.