Transmissions, gears, bearings, drive lines. Is there a particular thought you wanted an answer too. About the only time friction is desired, is during braking.
it can be harmful when you buy shoes and they are to tight and if your books and binders are really rough and you have a hard time sliding them into your back pack they will rub and cause friction
Friction slows down a car. As such, in order to maintain the velocity of the car, energy, i.e. gasoline, is required due to friction. If there were no friction, an impossible state, the car would...