Here's why:
* Static friction is the force that prevents an object from moving when it's at rest. It acts in the opposite direction of any force trying to start the object moving. Think of a heavy box on a floor: You have to push harder than the static friction to get it to budge.
* Kinetic friction is the force that opposes the motion of an object that is already moving. It's generally less than static friction, which is why it's easier to keep something moving than to start it moving.
So, to summarize:
* Static friction is the friction that needs to be overcome to *initiate* movement.
* Kinetic friction is the friction that opposes movement *while it's happening*.
