Ventilation

Ventilation is the intentional movement of air from outside a building to the inside. It is the V in HVAC. Movement of air between indoor spaces, and not the outside, is not ventilation this is called transfer air.

With clothes dryers, and combustion equipment such as water heaters, boilers, fireplaces and stoves their exhausts are often called vents or flues this should not be confused with ventilation. The vents or flues carry the products of combustion which have to be expelled from the building in a way which does not cause harm to the occupants of the building.