A great part of adolescence is the social transition teens all go through. As adolescence is the transition from childhood to adulthood, teens will be developing new types of social relationships with a broader range of people, and they will start understanding the different roles they hold relative to other people (e.g. child, student, sibling, athlete, etc).
One of the greatest social transitions is the new importance a teen's peer group will hold for him or her. First, teens will be more independent in choosing their own friends, spend considerably more time with their friends, and be more influenced by their friends and others in their peer group. The label of your teen's peer group (e.g. jocks, nerds, burn-outs, etc.) can have a great effect on your teen's self-esteem. Your teen's struggle to gain and maintain his/her self-esteem is a critical part of the social transition.
As part of finding their own group of friends and peer group, teens are working hard to develop their own social identity. This means clarifying their own unique set of tastes and preferences, usually through a wide-ranging process of experimentation. Teens develop their own social identity through the clothes they wear, their choices in music, movies, food, hairstyles, activities, as well as the friends they choose. Often, teens will explore these new options in concert with their friends. This is part of the teens' separation from their parents and their transition toward giving their friendships greater social importance.
Of course, the sexual development of teens means they'll begin developing romantic and/or sexual relationships with other teens. The learning steps through this transition occur as teens begin to focus more on the opposite sex, go out socially with the opposite sex, and start to pair off in a romantic way.