Rockets are vehicles designed to travel into space or deliver payloads, such as satellites, into orbit. They work by expelling gas at high speed in the opposite direction, following Newton's third law of motion: for every action, there is an equal and opposite reaction. Rockets can be powered by various types of fuel, including liquid and solid propellants. Rockets are used for various purposes, including scientific research, exploration, and military applications. Notable examples include the Saturn V, which took astronauts to the Moon, and the SpaceX Falcon 9, which is used for commercial satellite launches and resupply missions to the International Space Station.