The laws of motion were defined by Sir Isaac Newton. He outlined them in his book *Philosophiæ Naturalis Principia Mathematica* (Mathematical Principles of Natural Philosophy), published in 1687.

These laws are:

1. Newton's First Law of Motion (Law of Inertia): An object at rest stays at rest and an object in motion stays in motion with the same speed and in the same direction unless acted upon by an unbalanced force.

2. Newton's Second Law of Motion: The acceleration of an object is directly proportional to the net force acting on the object and inversely proportional to its mass.

3. Newton's Third Law of Motion: For every action, there is an equal and opposite reaction.