Newton's first law of motion, often referred to as the law of inertia, states:
"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 external force."
In simpler terms, this law describes how an object's motion will not change on its own. If an object is at rest, it will remain at rest unless something pushes or pulls it. Likewise, if an object is in motion, it will keep moving in the same direction and at the same speed unless a force acts upon it to change its motion. This law provides the foundation for understanding the behavior of objects in the absence of forces.