Ducts are tubes or channels that transport air, liquids, or other substances from one place to another. In homes, HVAC systems use ducts to circulate warm or cool air, ensuring comfort in different rooms. These ducts can be made of metal, plastic, or fiberglass, and they come in various sizes depending on their purpose. In addition to heating and cooling, ducts are also used in plumbing to carry water and waste. For example, ventilation ducts help remove stale air and bring in fresh air, improving indoor air quality. Overall, ducts play a crucial role in many systems that keep our environments functional and comfortable.