Every bathroom should have a bathroom exhaust fan for proper moisture control and ventilation. Exhaust fans have 2 different methods by which they can move air in your bathroom.
Propeller Fans, Also Known as Axial Fans
The first type of bathroom exhaust fan is the propeller, or axial fan, which is similar to a standard house fan. These exhaust fans are capable of moving a lot of air without requiring a lot of pressure.
The most common bathroom exhaust fan is the propeller fan because they are the most cost effective and compact. A disadvantage to the axial fan is that they are incapable of producing higher pressures.
The other type of bathroom exhaust fan is a centrifugal fan. They are quite similar in nature to centrifugal water pumps. They have a plate that has radial vanes. The air is forced out by centrifugal force.