Thrust is a force that propels an object forward. It is commonly associated with engines and propulsion systems, and is caused by the expulsion of mass in one direction, which generates an equal and opposite force in the opposite direction. In other words, thrust is the result of Newtons Third Law of Motion, which states that for every action, there is an equal and opposite reaction. In the context of engines, thrust is generated by the combustion of fuel, which produces hot gases that are expelled out of a nozzle at the back of the engine. The force of the expelled gases propels the engine and the object it is attached to forward.