Air ducts are passages used in heating, ventilation, and air conditioning (HVAC) systems to distribute air throughout a building. They are typically made of metal, fiberglass, or flexible plastic and can be found in various shapes and sizes. Properly designed air ducts help maintain comfortable indoor temperatures and improve air quality by circulating fresh air. In addition to their primary function, air ducts can also accumulate dust, allergens, and other pollutants over time. Regular maintenance, such as cleaning and inspections, is essential to ensure that the HVAC system operates efficiently and to promote a healthy indoor environment.