ARM processors support up to seven processor modes, depending on the architecture version. These are:

All modes except User mode are referred to as privileged modes.

Applications that require task protection usually execute in User mode. Some embedded applications might run entirely in Supervisor or System modes.

Modes other than User mode are entered to service exceptions, or to access privileged resources. Refer to the Handling Processor Exceptions chapter in ADS Developer Guide, and ARM Architecture Reference Manual for more information.