Initiation is a rite of passage marking entrance or acceptance into a group or society. It could also be a formal admission to adulthood in a community or one of its formal components. In an extended sense it can also signify a transformation in which the initiate is 'reborn' into a new role. Examples of initiation ceremonies might include Christian baptism or confirmation, Jewish bar or bat mitzvah, acceptance into a fraternal organization, secret society or religious order, or graduation from school or recruit training. A person taking the initiation ceremony in traditional rites, such as those depicted in these pictures, is called an initiate.
Read article on Wikipedia