Newton's first law says that an object at rest will stay at rest, while an object in motion will stay in motion unless acted upon by an outside force.
A great example of this is a ball sitting on the ground. The ball will not move until some force is used on it, rather that be you kicking it, the wind blowing it, etc. Once that force is used against it, the ball will continue to move until gravity, air resistance, a friction bring it to a stop.
