Practiced among the Yoruba, Ifa divination relies on a complex system of signs, compiled in a literary corpus (Odu Ifá), that are interpreted by a diviner to guide important personal or collective decisions. The Ifa divination system, which makes use of an extensive corpus of texts and mathematical formulas, is practiced among Yoruba communities. Contrary to other forms of divination, it does not rely on a person having oracular powers but rather on a system of signs that are interpreted by a diviner, the Ifa priest or babalawo. The divination tray used is called Opon Ifá, used by a Babalawo to communicate with the spirits. Opon Ifás are flat and usually circular, with a raised outer edge carved with figures, objects or geometric designs. The top of the tray is called the head, and the bottom the foot. The head is normally carved with a representation of Eshu, the messenger of Ifá and the other spirits.