What exactally is a rocket engine?

A rocket engine is a propulsion system that generates thrust by expelling mass at high velocity, typically through the combustion of propellants. It operates on Newton's third law of motion, where the reaction force from the expelled gases propels the rocket in the opposite direction. Rocket engines can be classified into two main types: liquid engines, which use liquid propellants, and solid engines, which use solid propellant compositions. These engines are essential for launching spacecraft and carrying payloads beyond Earth's atmosphere.