What is the main function of propulsive thrust in aircraft?

Propulsion is defined as pushing forward or driving a thing forward, and a machine that produces thrust/force to push the object is called a propulsion machine. In airplanes, the propulsion is generated with the help of gas or fluid. An engine in the airplane accelerates the gas, and in reaction to it, acceleration produces a force on the engine. The amount of thrust produced depends on mass flow and the exit velocity of the gas. Thrust is applied by using Newton's third law of motion. Its SI unit is Newton.

There is four major propulsion system, which is mentioned below:

1. Propeller system
2. Turbine engine
3. Ramjet system
4. Rocket system