The Pāli Tipitaka, which means "three baskets", refers to the Vinaya Pitaka, the Sutta Pitaka, and the Abhidhamma Pitaka. The Vinaya Pitaka contains disciplinary rules for the Buddhist monks and nuns, as well as explanations of why and how these rules were instituted, supporting material, and doctrinal clarification. The Sutta Pitaka contains discourses ascribed to Gautama Buddha. The Abhidhamma Pitaka contains material often described as systematic expositions of the Gautama Buddha's teachings.