Give two examples of friction being a useful force

Can start a fire (rubbing to rocks together) and friction is used when you hit the brakes on a car (the pad pushes down on the tire). Good luck!

Friction is useful for walking. We would never stop going. We would constantly be slipping. and clothes would be very difficult

It is also useful for grabbing. Imagine trying to grab an oiled up phone. It would slip out of your hands! Everything would be like that without friction