"Dystopian" has become a buzz word in publishing circles. It means a society characterized by human misery. The stories involve a bleak future, oppressive forces, and protagonists facing difficult choices.
Here is a great article by a child and adolescent psychiatrist stating why this style of literature appeals to teens, considering their developmental tasks of separation from parents, and their emotional and hormonal upheaval. Great information for parents as well as for fans of literature.