What is a hierarchy?

A hierarchy is the classification of a group of people according to ability or to economic, social, or professional standing; pecking order, chain of command.

Doug was the star of both the junior varsity soccer team and the lacrosse team. In the social hierarchy of Ithaca High School, Doug reigned with a status and popularity unmatched by his classmates. Alexa was far too shy to pursue a friendship with a boy like Doug, but the proximity of their houses made it natural for them to carpool together.

From Karen Chapman's The Marino Mission.