Aaronic Priesthood

Also known as the lesser priesthood. It serves as the entry point into the priesthood for boys age twelve and older as well as adult male converts. Members of this priesthood supposedly experience the ministering of angels. The Aaronic priesthood is responsible for the churchs temporal affairs under the guidance of the bishop. 

Biblical Christianity teaches that the Aaronic or Levitical priesthood was replaced by the Melchizedek priesthood (which only has one priest, Jesus Christ) and no longer exists. See Hebrews 7:15-19.