Rocket boosters are powerful engines designed to provide the initial thrust needed to launch a rocket into space. They work by burning fuel to produce a large amount of hot gas, which is expelled at high speed, propelling the rocket upward. Boosters are typically used during the first phase of a launch, helping the rocket overcome Earth's gravity. Once the rocket reaches a certain altitude and speed, the boosters are jettisoned to reduce weight. This allows the remaining stages of the rocket, such as the main engine, to continue the journey into space. Common examples of rocket boosters include those used in the Space Shuttle and the Falcon 9 rocket.