Here's how it works:

* Burning Fuel: Rockets carry fuel and an oxidizer (like liquid oxygen). When ignited, they burn rapidly, producing hot gas.

* Nozzle Expansion: This hot gas is expelled through a nozzle, which is designed to expand the gas, increasing its velocity.

* Newton's Third Law: The rapid expulsion of gas creates a force in the opposite direction, pushing the rocket forward. This is the principle of action and reaction, as stated by Newton's third law of motion.

In simpler terms: Imagine blowing up a balloon. When you let go, the air rushes out, pushing the balloon in the opposite direction. A rocket works on the same principle, but on a much larger scale, using burning fuel to create the force of thrust.