Erik erikson's fifth developmental stage, which individuals experience during adolescence, is

Identity vs. Role Confusion; adolescents search for their sexual & occupational identity through the exploration of their goals, beliefs, and values. If an adolescent fails to establish a sense of identity, he feels unsure of himself and/or his place in society(role confusion/identity crisis).

An informal structure in a bureaucracy would be something like so-called "office politics". where there's a formal structure set up for the organization, but then an informal subculture as well that has a way of organizing the bureaucracy further. this can be positive because it sets up an added degree of organization, albeit informal, within the bureaucracy.