If you don’t live in a hilly region, odds are you don’t often use your parking, or emergency brake. The parking brake helps keep the transmission in place while the car is parked in stopped, and puts a stronger hold than simply putting it in park. The brake bypasses the hydraulic braking system, stops the car in an emergency or keeps it in place while parked. Also if the car is hit while parked, the parking brake helps to stabilize it.
If you do use the parking brake, it’s important to disengage or release it when you’re in drive. Not doing so can lead to damage to your transmission. The parking brake is important for all the reasons above so remember, it’s there for a good reason!