Rocketry is the science and technology of designing, building, and launching rockets. Rockets are vehicles that use controlled explosions to propel themselves into the sky. They work on the principle of Newton's Third Law of Motion, which states that for every action, there is an equal and opposite reaction. This means that when a rocket expels gas downwards, it moves upwards. The field of rocketry has many applications, including space exploration, satellite deployment, and military uses. Notable figures in rocketry include Robert H. Goddard, who is often called the father of modern rocketry, and Wernher von Braun, who played a key role in developing rockets for space travel.