The Blackfoot Confederacy, Niitsitapi, or Siksikaitsitapi, is a historic collective name for linguistically related groups that make up the Blackfoot or Blackfeet people: the Siksika ("Blackfoot"), the Kainai or Blood, and two sections of the Peigan or Piikani – the Northern Piikani (Aapátohsipikáni) and the Southern Piikani. Broader definitions include groups such as the Tsúùtínà (Sarcee) and A'aninin who spoke quite different languages but allied with or joined the Blackfoot Confederacy.

The Blackfoot language, also called Siksiká, often anglicised as Siksika, is an Algonquian language spoken by the Blackfoot or Niitsitapi people, who currently live in the northwestern plains of North America. There are four dialects, three of which are spoken in Alberta, Canada, and one of which is spoken in the United States: Siksiká (Blackfoot), to the southeast of Calgary, Alberta; Kainai, spoken in Alberta between Cardston and Lethbridge; Aapátohsipikani, to the west of Fort MacLeod which is Brocket (Piikani) and Aamsskáápipikani, in northwestern Montana. The name Blackfoot probably comes from the blackened soles of the leather shoes that the people wore.