Final answer:
Newton's Third Law of Motion states that for every action, there's an equal and opposite reaction, which means two interacting bodies exert forces that are equal in magnitude and opposite in direction on each other.
Step-by-step explanation:
Newton's Third Law of Motion is a fundamental principle that applies whenever two bodies interact. This law states that for every action, there is an equal and opposite reaction. In other words, if one object exerts a force on a second object, the second object simultaneously exerts a force back on the first object that is of equal magnitude but in the opposite direction. These forces are called action-reaction pairs. It's important to note that even though these forces are equal and opposite, they act on different bodies and therefore don't cancel each other out.
For example, when you sit on a chair, your body exerts a downward force on the chair due to gravity, and the chair exerts an upward force on your body that is equal in magnitude but directed upwards. This upward force is often referred to as the normal force. Both of these forces are an illustration of Newton's Third Law of Motion at work.