Nusach Sefard is the most common type of siddur among Chassidic Jews (sometimes spelled Sepharad or Sfard). It developed to incorporate many of the kabbalistic teachings of the Ari (Rabbi Isaac Luria) into the established Ashkenazi liturgy, incorporating the wording of Nusach Edot HaMizrach (the prayer book of Sephardic Jews) into certain prayers. Nusach Sefard is used nearly universally by Chassidim, as well as by some other Ashkenazi Jews.