Details: This poster is of Office Fan, by Paula Scaletta. It shows an old-fashioned fan against a beige background. At the bottom it says: fan (fan), n.
A fan is a powered device used to create flow within a gas, usually air. A fan consists of a rotating arrangement of vanes or blades which act on the air. Usually it is contained within some form of housing or case. This may direct the airflow or increase safety by preventing objects from contacting the fan blades. Most fans are powered by electric motors, but other sources of power may be used, including hydraulic motors and internal combustion engines.