How does Newton’s third law explain action and reaction forces?

Newton’s third law of motion states that for every action, there is always an opposed and equal reaction; essentially, when one body exerts a force on a second body, the second body simultaneously exerts a force of equal magnitude and opposite direction on the first.123

A critical aspect of this principle is that action and reaction forces always act on different bodies, meaning they never produce a net force on a two-body system as a whole. This law applies regardless of whether the objects are at rest, in uniform motion, or accelerating.1

It is important to distinguish these pairs from forces acting on the same body. For example, an object resting on a table is in equilibrium because the downward force of gravity is balanced by an upward force from the table. While these two forces are equal and opposite, they act on the same body and are not an action-reaction pair. The true action-reaction pair involves the object exerting a downward force on the table and the table exerting an equal upward force on the object.1