Vehicles have cooling fans that allow them to control temperature and make the vehicle run smoothly, especially during hot seasons when there the air around is not enough to go through the radiator core. A cooling fan is also needed whenever you are not driving fast enough, because it also means not enough air rushes through the grille of your car. Fans are usually mounted on the water pump water shaft, but they may be mounted as independent units.
Every vehicle has at least one fan. That is how vital it is, but some vehicles have more than one to ensure their cooling systems are superb. There are belt-powered fans, electric fans, and AC cooling fans. Electric fans are more modern as they don't have fan belts for you to keep a constant eye on. They are also quieter and consume less power than other fans.
Primary cooling fans use a thermostatic control called a fan clutch to determine the right speed of their spin. The fan clutch signals the cooling fan to run faster when heat is accumulating in the engine and tells it to go slower or stop altogether when enough air is coming through the radiator. This renders the fan unnecessary. Cooling fans drain power from the engine in order to spin, and so they shouldn't be left to spin all the time.
Most fans are made of tough plastic and have four to six blades, although others have as much as eleven. Often the blades are enclosed in a fan shroud to keep the same hot air from going through and around it again.