A duct system is a network of tubes or channels used to distribute air throughout a building. It is an essential part of heating, ventilation, and air conditioning (HVAC) systems, helping to maintain comfortable indoor temperatures and air quality. Ducts can be made from various materials, including metal, fiberglass, and flexible plastic. These systems can be designed in different configurations, such as supply ducts that deliver conditioned air and return ducts that bring air back to the HVAC unit for reconditioning. Properly designed and maintained duct systems improve energy efficiency and ensure even airflow in residential and commercial spaces.