HVAC stands for Heating, Ventilation, and Air Conditioning. It is a system that is used to regulate the temperature, humidity, and air quality of a space. HVAC systems typically consist of a furnace, air conditioner, and ductwork. The furnace is used to heat the air, while the air conditioner is used to cool the air. The ductwork is used to distribute the air throughout the space. HVAC systems are used in both residential and commercial buildings to ensure a comfortable environment.