The definition of HVAC (Heating, Ventilation, and Air Conditioning) is a system of technologies used to maintain comfortable indoor air temperatures and air quality. HVAC systems are designed to regulate temperature, humidity, air quality, and air movement. HVAC systems are used in both residential and commercial buildings to provide a comfortable environment for occupants. The components of an HVAC system include an air handler, an evaporator coil, a condenser coil, a blower, and a thermostat. The air handler circulates air throughout the building, while the evaporator coil cools the air. The condenser coil removes heat from the air, and the blower circulates the air throughout the building. The thermostat controls the temperature of the air, and the air quality is maintained by the use of filters. HVAC systems are essential for providing a comfortable and healthy environment for occupants, and they are used in a variety of settings, from homes to office buildings.