The Salafi movement or Salafist movement is an ultra-conservative reform movement within Sunni Islam that references the doctrine known as Salafism. The doctrine can be summed up as taking "a fundamentalist approach to Islam, emulating the Prophet Muhammad and his earliest followers—al-salaf al-salih, the 'pious forefathers'...They reject religious innovation, or bida, and support the implementation of sharia (Islamic law)." The movement is often divided into three categories: the largest group are the purists (or quietists), who avoid politics; the second largest group are the activists, who get involved in politics; the smallest group are the jihadists, who form a small (yet infamous) minority.