If no net force acts on an object, its motion remains unchanged. This is a fundamental principle of physics known as Newton's First Law of Motion, also called the Law of Inertia.

Here's what it means:

* At rest, it stays at rest: If an object is stationary, it will stay stationary unless a force acts upon it. Think of a book on a table. It will stay put until you push it.

* In motion, it stays in motion: If an object is moving, it will continue moving at the same speed and in the same direction unless a force acts upon it. Imagine a ball rolling across a smooth, frictionless surface. It would keep rolling forever without slowing down or changing direction.

Important points:

* Net force: This refers to the overall force acting on an object. If multiple forces act on an object, they might cancel each other out, resulting in no net force.

* Friction: In real-world scenarios, friction is often present, slowing down objects in motion. However, Newton's First Law still applies – friction is simply a force that changes the motion of the object.

In summary, without a net force, an object will either remain at rest or continue moving at a constant velocity (speed and direction).