The auxiliary (parking/hand) brake may also be used:

1. To reduce wear and tear of the braking system.
2. Correct answer: As an emergency brake .
3. To prevent the vehicle from moving only.
4. To assist drivers while driving in reverse.

WhyThe handbrake holds the car when parked. While moving it can serve as an emergency brake, but a weak one: it does not act on all the wheels. It is not meant for descents or reversing.