Propulsion methods refer to the various techniques used to move vehicles, such as ships, airplanes, and rockets. Common methods include internal combustion engines, which burn fuel to create motion, and electric motors, which use electricity to generate movement. Another popular propulsion method is jet propulsion, where engines expel gas at high speed to push the vehicle forward. Additionally, rocket propulsion relies on the expulsion of gas from a combustion chamber, allowing spacecraft to travel in the vacuum of space. Each method has its own advantages and applications depending on the vehicle and environment.