Kinetic friction is the frictional force that opposes the motion of an object that is already moving. It's the friction you feel when you slide a box across the floor or push a heavy object.

The frictional force needed to start an object at rest into motion is called static friction. It's the force that keeps the object from moving until you overcome its resistance.

Here's a simple breakdown:

* Static Friction: The force that prevents an object from moving when it's at rest. It's like the "sticking" force.

* Kinetic Friction: The force that opposes the motion of an object that's already moving. It's like the "sliding" force.

Let me know if you'd like to learn more about these types of friction!