Catharism (/ˈkæθərɪzəm/; from the Greek: καθαροί, katharoi, "the pure [ones]") was a Christian dualist or Gnostic revival movement that thrived in some areas of Southern Europe, particularly northern Italy and southern France, between the 12th and 14th centuries. The followers were known as Cathars and are now mainly remembered for a prolonged period of persecution by the Catholic Church which did not recognise their belief as truly Christian. It appeared in Europe in the Languedoc region of France in the 11th century and this is when the name first appears. The adherents were also sometimes known as Albigensians after the city Albi in southern France where the movement first took hold. The beliefs are believed to have been brought from Persia or the Byzantine Empire.
Cathar beliefs varied between communities, because Catharism was initially taught by ascetic priests who had set few guidelines. The Catholic Church denounced its practices including the Consolamentum ritual, by which Cathar individuals were baptized and raised to the status of 'perfect'.
Catharism had its roots in the Paulician movement in Armenia and eastern Byzantine Anatolia and the Bogomils of the First Bulgarian Empire, who were influenced by the Paulicians resettled in Thrace (Philipopolis) by the Byzantines. Though the term "Cathar" (/ˈkæθɑːr/) has been used for centuries to identify the movement, whether the movement identified itself with this name is debatable. In Cathar texts, the terms "Good Men" (Bons Hommes) or "Good Christians" are the common terms of self-identification.