AZA is the commonly used acronym for Aleph Zadik Aleph, an international Jewish youth group.
AZA was founded in 1922 by a group of 14 young Jewish men who wished to join a fraternity at their school: Alpha Zeta Alpha. They were denied membership on account of their religion, and, to spite the fraternity, they started one of their own, breaking the tradition of using Greek letters. The fraternity was known as Aleph Zadik Aleph, all Hebrew letters.
Starting out from this first "mother chapter" the organization began to spread to other cities. The members dreamt of having an international order. In 1925, they petitioned a much larger organization for adults, B'nai B'rith International to adopt them as a junior order. The petition was accepted.
AZA is now an international organization, with chapters in many countries. It is part of BBYO, the B'nai B'rith Youth Organization, along with BBG, the youth order for girls. It is a self-governing group divided into chapters, councils, regions, and the international government. AZA requires members to adhere to 7 cardinal principals:
Patriotism
Judaism
Filial Love
Charity
Conduct
Purity
Fraternity
Basically anyone can become a member, provided that they have a Jewish father.