A sweat lodge is a low profile hut, typically dome-shaped or oblong, and made with natural materials. The structure is the lodge, and the ceremony performed within the structure may be called by some cultures a purification ceremony or simply a sweat. Traditionally the structure is simple, constructed of saplings covered with blankets and sometimes animal skins. Originally, it was only used by some of the Indigenous peoples of the Americas, notably the Plains Indians, but with the rise of pan-Indianism, numerous nations that did not originally have the sweat lodge ceremony have adopted it. This has been controversial.

In all cases, the sweat is intended as a spiritual ceremony – it is for prayer and healing, and the ceremony is only to be led by elders who know the associated language, songs, traditions, and safety protocols. Otherwise, the ceremony can be dangerous if performed improperly.

Sweat lodges have also been imitated by some non-natives in North America and internationally, resulting in responses like the Lakota Declaration of War and similar statements from Indigenous Elders declaring that these imitations are dangerous and disrespectful misappropriations and need to stop.