Vodou has a single creator, Bondye, whose name comes from the French bon Dieu. Bondye is not doubted and not petitioned. He is understood to have made the world and to be too vast and too distant to be troubled with a particular person's illness, lawsuit or harvest. Those matters belong to the lwa, several hundred named spirits who stand between people and God, each with a character, a set of preferences, a colour, a day, a drum rhythm and a drawn ground-sign, the veve, that calls it.
The lwa are grouped into nanchon, nations, a term preserving the memory of the different African peoples whose traditions fed the religion. Two dominate. The Rada lwa are cool, deliberate and associated with Dahomean and Yoruba origins: Danbala the serpent, Ezili Freda, Legba who opens the way and is greeted first. The Petwo lwa are hot, fast and demanding, drawing heavily on Kongo material and generally understood as forged in the colony itself; Ezili Danto belongs here, as do the Gede spirits of the dead. Neither group is good or evil. The distinction is one of temperature, and of what a spirit will do and what it will require in return.
Relations with the lwa are reciprocal and close to contractual. A person inherits obligations to the spirits of their family line and takes on others through service. The spirits are fed, saluted and entertained; they answer with protection, healing, warning and practical advice, and they punish neglect.
The central event is possession. During a ceremony a lwa mounts a devotee, who is called the chwal, the horse, and speaks and acts in its own manner through that person, greeting the congregation, scolding, diagnosing and prescribing. The one mounted is not held to remember it afterwards. Vodou treats this not as a loss of self but as the most direct contact available, and what the spirit says is taken seriously by everyone present.