A bong is a type of smoking device used for consuming cannabis or other substances. It typically consists of an upright stem with a water reservoir at the base, and a cylindrical tube that connects to a mouthpiece on top. When smoke is drawn through the water in the bong's chamber, it cools down the hot smoke, resulting in a smoother hit for the user. The term "bong" can also refer to any large container used for smoking or other purposes.