1. Opposes Motion: Friction acts in the opposite direction of the motion of an object, making it harder for the object to move. This is why it takes more force to push a heavy box across a rough floor than a smooth floor.

2. Converts Energy to Heat: Friction converts kinetic energy (energy of motion) into heat energy. This is why rubbing your hands together makes them warm, or why brakes get hot when you use them to slow down a car.