HVAC stands for Heating, Ventilation, and Air Conditioning, and is a term used to describe a system that provides thermal comfort and indoor air quality. It is a system that is used to control the temperature, humidity, and air quality of a space, and is typically used in commercial and residential buildings. HVAC systems are made up of several components, including a furnace, air conditioner, air handler, evaporator coil, and thermostat. The furnace is responsible for heating the air, while the air conditioner cools it. The air handler moves the air throughout the space, while the evaporator coil absorbs the moisture from the air. Finally, the thermostat controls the temperature of the space. HVAC systems are designed to provide a comfortable environment for occupants, and are essential for ensuring that the air quality in a space is safe and healthy.