Priest hood

The Aaronic priesthood (also called the Levitical priesthood) is the lesser of the two (or sometimes three) orders of priesthood recognized in Mormonism. The others are the Melchizedek priesthood and the rarely-recognized Patriarchal priesthood. Unlike the Melchizedek Priesthood, which is modeled after the authority of Jesus and the Apostles, or the Patriarchal Priesthood, which is modeled after the authority of Abraham, the Aaronic Priesthood is modeled after the priesthood of Aaron the Levite, the first high priest of the Hebrews, and his descendents. The Aaronic Priesthood is thought to be a "branch" or an "appendage" of the more powerful Melchizedek Priesthood. Practically, they are administrative and financial agents of the church
In The Church of Jesus Christ of Latter-day Saints, the Aaronic Priesthood has taken on a role as a source of training, leadership and service for adolescent boys and new converts. It is often called a "preparatory priesthood." Holders of the Aaronic priesthood whom the church considers worthy are advanced to an office in the Melchizedek priesthood as a matter of course around the age of 18, or in the case of adult converts, after approximately a year of active church membership.The Aaronic priesthood is open only to men and boys, twelve years old or older, who are considered worthy after a personal interview with a local bishop.
Requirements for worthiness include abstaining from certain sexual practices, following the Word of Wisdom (a code requiring abstinence from drinking, smoking, and consumption of coffee and tea), and attending church services.With the exception of bishop, the offices of the Aaronic priesthood are organized primarily by age, and an adolescent boy will automatically advance to the next office if found worthy upon reaching the appropriate age. The conferral and ordination to an office in the Aaronic priesthood is performed by the "laying on of hands" by a Priest or by those holding the Melchizedek priesthood.
With the exception of bishop Aaronic priesthood holders of the same office are organized into a quorum led by a president and counselors within each quorum. The president of the Priests Quorum is the bishop or branch president of the congregation. Each ward has one or more quorums of each office of the priesthood, if there are young men in that age group among the membership.The church-wide titular head of the Aaronic priesthood is the Presiding Bishop. However, because the Aaronic priesthood is composed primarily of the youth of the church, the presidency of the Young Men Organization supervises much of the church-wide organization involving the Aaronic priesthood.