Here's a breakdown:

* Friction is the force that opposes motion between two surfaces in contact.

* Coefficient of friction is a dimensionless quantity that represents the ratio of the frictional force to the normal force pressing the surfaces together.

It's important to note that there are two main types of friction:

* Static friction: The friction that prevents an object from moving when a force is applied to it.

* Kinetic friction: The friction that opposes the motion of an object that is already moving.

Each type of friction has its own coefficient.