Newton's third law states that if one object exerts a force on a second, the second exerts a force that is:

1. Forces always come in pairs between interacting objects. 2. If one object exerts a force on a second object, the second object always exerts a force of equal magnitude on the first object. 3. That returning force acts in the opposite direction. 4. The two forces act on different objects, which is why they do not simply cancel. _Source: OpenStax College Physics for AP(R) Courses 2e (CC BY 4.0), Ch 4 'Dynamics: Force and Newton's Laws of Motion', sections 4.1-4.8_