A bong (also known as a water pipe) is a filtration device generally used for smoking cannabis, tobacco, or other herbal substances. In the bong shown in the photo, the gas flows from the lower port on the left to the upper port on the right.
In construction and function, a bong is similar to a hookah, except smaller and especially more portable. A bong may be constructed from any air- and water-tight vessel by adding a bowl and stem apparatus (or slide) which guides air downward to below water level whence it bubbles upward ("bubbler") during use. To get fresh air into the bong and harvest the last remaining smoke, a hole known as the "carburetor", "carb", "choke", "bink", "rush", "shotty", "kick hole", or simply "hole", somewhere on the lower part of the bong above water level, is first kept covered during the smoking process, then opened to allow the smoke to be drawn into the respiratory system. On bongs without such a hole, the bowl and/or the stem are removed to allow air from the hole that holds the stem.
Bongs have been in use by the Hmong in Laos and Thailand, as well all over Africa, for centuries. One of the earliest recorded uses of the word in the West is in the McFarland Thai-English Dictionary, published in 1944, which describes one of the meanings of bong in the Thai language as, "a bamboo waterpipe for smoking kancha, tree, hashish, or the hemp-plant." A January 1971 issue of the Marijuana Review also used the term.