In engineering and physical sciences, a chimney is a structure designed to facilitate the safe expulsion of combustion gases, smoke, and particulates from a heat source, such as a furnace or boiler. Functionally, these structures rely on the principle of thermal convection, where the hot, buoyant gases are naturally drawn upward through the flue passage, creating a draft. The design and construction of chimneys must account for material science considerations, including resistance to extreme temperatures and corrosive byproducts, as well as adherence to fluid dynamics principles to ensure adequate draft and efficient ventilation. Modern implementations incorporate various venting technologies to improve energy efficiency and minimize pollutant dispersion into the surrounding atmosphere.