Here's a breakdown:

* Heat (h): Friction is a force that resists motion between two surfaces in contact. When these surfaces rub against each other, the energy of motion is converted into heat energy. This is why you feel heat when you rub your hands together.

* Wear (n): Friction can also cause wear and tear on the surfaces in contact. The repeated rubbing can cause materials to erode, scratch, or even break down completely.

Examples:

* Brakes: The friction between brake pads and the brake rotor generates heat, slowing the car down. Over time, the brake pads wear down.

* Rubbing your hands together: The friction produces heat.

* A tire rolling on the road: The friction between the tire and the road produces heat and wear on the tire.

It's important to note that friction can be both beneficial and detrimental depending on the situation.