Here's how it works:

* Rocket engines burn fuel, creating hot, expanding gas.

* This gas is expelled out of the rocket nozzle at high speed.

* According to Newton's Third Law of Motion, for every action, there is an equal and opposite reaction.

* The expulsion of the gas creates an equal and opposite force pushing the rocket in the opposite direction – this is thrust.

In simpler terms, the rocket pushes the gas out, and the gas pushes the rocket back. This force of thrust is what allows rockets to overcome gravity and travel into space.