Air flow refers to the movement or circulation of air, either naturally caused by wind or artificially created through mechanical means such as fans and ventilation systems. It is a measure of how much air moves past a point in a given amount of time, typically measured in cubic feet per minute (CFM) or meters cubed per second (m3/s). Air flow can be influenced by factors such as temperature, humidity, altitude and wind speed, among others. In the context of HVAC systems, air flow is an essential component for maintaining indoor air quality and ensuring proper distribution of conditioned or heated air throughout a building.