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A fire pit or a fire hole can vary from a pit dug in the ground to an elaborate gas burning structure of stone, brick, and metal. The common feature of fire pits is that they are designed to contain fire and prevent it from spreading.
Pre-made fire pits are the most common form of fire pits and can be purchased from a store. These are made mostly of metal and can be either wood or gas burning. Unlike traditional fire pits, these fire pits are portable.
Assembled fire pits are different from pre-made fire pits and because they are built according to an individual's wishes, they encompass a wider variety of styles and functions. Both stone and concrete fire pits are very heavy and are essentially locked into wherever they are placed. Both wood and gas may be used as fuel sources. In lieu of wood as an aesthetic, gas fire pits use a variety of mediums (gas logs, fire glass, stones, etc.) to retain heat and obscure the internal plumbing of the fire pit.
Essentially, to make a fire pit only a hole is required in order to safely contain a fire. This can be as simple as digging a hole in the ground, or as complex as hollowing out a brick or rock pillar.
Keep in mind, fire pits should be located at least 10 feet away from structures for safety. You should also avoid windy conditions, and always keep a container of water nearby in case of emergency. 
The Dakota smokeless fire pit
An aerated scheme for building a fire with little or no smoke is known by camping and scouting experts as the Dakota fire pit. As depicted in the illustration, two small holes are dug in the ground, one for the firewood the other for a draft of air. Small twigs are stuffed into the fire hole and then on top an easy burning layer of scrap is set. The fire burns from the top downward, dragging air from the "air hole" as it burns. Because the air passes inside the wood the CO gas is consumed burning strongly and brightly and with little or no seen smoke. The Dakota fire pit is a tactical fire used by the United States Marine Corps as the flame produces a low light signature, reduced smoke, and is easier to ignite under strong wind conditions. 
Fire pits in history
Many cultures, particularly nomadic ones would cut the turf above the fire-pit in a turf cutting ceremony, replacing the turf afterwards to hide any evidence of the fire. Elements of this ceremony remain in traditional youth organisations such as the Woodcraft Folk.
The remains of fire pits preserve information about past cultures. Radiocarbon dating from charcoal found in old fire pits can estimate when regions were first populated or when civilizations died out. Bones and seeds found in fire pits indicate the diet of that area.
In archaeological terms fire pits are referred to as features because they can be seen and recorded as part of the site but cannot be moved without being destroyed.
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