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

In simpler terms, when one object pushes or pulls on another object (the action), the second object pushes or pulls back on the first object with the same force, but in the opposite direction (the reaction).

Here's a breakdown:

* Action: Object A exerts a force on Object B.

* Reaction: Object B exerts an equal and opposite force on Object A.

Examples:

* Jumping: When you jump, your feet push down on the ground (action). The ground, in turn, pushes back up on your feet with the same force (reaction). This is what propels you upwards.

* Rocket Launch: A rocket engine expels hot gases downwards (action). The gases, in turn, push back on the rocket with an equal and opposite force (reaction), propelling the rocket upwards.

* Walking: When you walk, your feet push backwards on the ground (action). The ground pushes forward on your feet with the same force (reaction), allowing you to move forward.

Important Note: Newton's Third Law applies to all forces, including gravitational, electromagnetic, and nuclear forces. It is a fundamental principle in physics and plays a crucial role in understanding the interactions between objects.