Thrust reversal principle in Aircrafts

Thrust reversal, also called reverse thrust, is the temporary diversion of an aircraft engine’s exhaust so that it is directed forward, rather than backwards. Reverse thrust acts against the forward travel of the aircraft, providing deceleration. Thrust reverser systems are featured on many jet aircraft to help slow down just after touch-down, reducing wear on the brakes and enabling shorter landing distances. Such devices affect the aircraft significantly and are considered important for safe operations by airlines.
Reverse thrust is also available on many propeller-driven aircraft through reversing the controllable-pitch propellers to a negative angle. The equivalent concept for a ship is called astern propulsion.

Disclaimer: As obtained from the Internet