Manitou, rendered manidoo in Ojibwe and with cognate forms across the Algonquian language family, names both the countless individual spirits understood to inhabit and animate the natural world, animals, plants, rivers, rocks, weather and celestial bodies among them, and, in many accounts, a single great overarching spirit, Gitche Manitou ("Great Spirit" or "Great Mystery"), understood as the ultimate source from which the lesser manitous derive. Basil Johnston's account of Ojibwe spiritual life, The Manitous, documents in detail how manitous were understood to populate every part of the natural and social world, each with its own character, powers and proper relationship to human beings, some benevolent, some dangerous, and most simply requiring careful, respectful conduct rather than either worship or fear alone.
A central traditional practice associated with manitou across many Algonquian peoples is the vision quest, in which typically a young person undertakes a period of fasting and solitude, often on a specially chosen site, in the hope of receiving contact with and the lifelong protection of a particular guardian manitou, an experience understood to shape the individual's identity and role within the community thereafter. Offerings of tobacco and other respectful protocols toward manitous, before hunting, gathering, or entering certain places, remain part of living practice among many Algonquian communities today, continuous with practices documented over centuries.