The principle of how rockets work is based on Newton's Third Law of Motion, which states:

For every action, there is an equal and opposite reaction.

Here's how it applies to rockets:

* Action: The rocket expels hot, high-pressure gas out of its nozzle.

* Reaction: The gas pushes back on the rocket, propelling it forward.

The rocket engine burns fuel, creating hot, expanding gases. These gases are directed out of the nozzle, creating a force in one direction (the action). This force is balanced by an equal and opposite force pushing the rocket in the opposite direction (the reaction). This is how rockets are able to generate thrust and travel through space.