A
rocket (Italian
rocchetta‚ "little fuse") is a
missile,
spacecraft,
aircraft or other
vehicle that obtains
thrust from a
rocket engine. Rocket engine exhaust is formed entirely from
propellant carried within the rocket before use. Rocket engines work by
action and reaction and push rockets forward simply by expelling their exhaust in the opposite direction at high speed, and can therefore work in the vacuum of space.