The Sweat Lodge is a Native American ceremonial sauna or steam bath. The Lakota term for sweat lodge is Inipi which means 'to live again'. Inipi is a purification rite and is necessary in order to help the vision quest seeker enter into a state of humility and to undergo a kind of spiritual rebirth.
The sweat lodge is central to Inipi. Prayers offered there draw on all the powers of the universe — Earth, Water, Fire and Air. In the old days, Inipi was done before any major undertaking to purify the body and gain strength and power.
The actual lodge itself is a dome constructed of 16 young willow trees placed in a circle, traditionally covered with hides so no light could penetrate inside.
On the outside, the formation of the site comprises an earth mound just outside the door of the sweat lodge, facing east, and a fire pit containing stones. The fire represents the sun. Another mound partially encircling the fire pit represents the crescent moon. This is the outer world or cosmos; the inner world is the sweat lodge. It represents the womb of the universe from which souls are created anew.
Prayers are said at each stage of the construction of a sweat lodge. When it is completed, a burning coal is brought in and sweetgrass is burned by the leader of the Inipi to purify the lodge. The pipe is smoked and carried outside, where it is placed on the mound of earth.
The other participants enter the lodge, sitting in a circle on sacred sage, and the Pipe is brought in and smoked. The heated rocks are placed on the center fireplace and the Pipe returned to the earth mound. Then, the door is closed.
During the ritual, the door is thrown open four times to represent the four ages described by the Sacred White Buffalo Calf Woman. The fourth time, participants leave the lodge, emerging from dark to light which represents the liberation from the physical universe. All that is impure is left in the sweat lodge.