Most wipers have a low and a high speed, as well as an intermittent setting. When the wipers are on low and high speed, the motor runs continuously. But in the intermittent setting, the wipers stop momentarily between each wipe. There are many different kinds of switches for wipers. Some cars have just one intermittent speed, others have 10 discrete settings and still others have a sliding scale that can be set for almost any time interval.
Whichever kind of controls your car has, setting them just right can be tricky -- too fast and the windshield gets dry and the wipers squeak; too slow and your visibility is blocked by raindrops. Compounding this is the fact that the amount of water hitting the windshield changes as your car speeds up and slows down. It can require almost constant attention to keep the wipers operating properly. Carmakers may finally have conquered this problem with the holy grail of wiper technology -- the rain-sensing wiper.