The four stages of enlightenment in Buddhism are the four progressive stages culminating in full enlightenment as an Arahat. These four stages are Sotapanna, Sakadagami, Anagami, and Arahat. The Buddha referred to people who are at one of these four stages as noble people (ariya-puggala) and the community of such persons as the noble sangha (ariya-sangha).
In Pali suttras several types of Buddhist practitioners are described, according to their level of attainment. The standard is four, but there are also longer descriptions with more types. The four are the Stream-enterer, Once-returner, Non-returner and the Arahat.
In the Visuddhimagga the four stages are the culmination of the seven purifications. The descriptions are elaborated and harmonized, giving the same sequence of purifications before attaining each of the four paths and fruits.
