Adolescence is a transitional stage of physical and psychological human development generally occurring between puberty and legal adulthood (age of majority). The period of adolescence is most closely associated with the teenage years, although its physical, psychological and cultural expressions can begin earlier and end later. For example, although puberty has been historically associated with the onset of adolescent development, it now typically begins prior to the teenage years and there has been a normative shift of it occurring in preadolescence, particularly in females (see early and precocious puberty). Physical growth, as distinct from puberty (particularly in males), and cognitive development generally seen in adolescence, can also extend into the early twenties. Thus chronological age provides only a rough marker of adolescence, and scholars have found it difficult to agree upon a precise definition of adolescence. A thorough understanding of adolescence in society depends on information from various perspectives, most importantly from the areas of psychology, biology, history, sociology, education, and anthropology. Within all of these perspectives, adolescence is viewed as a transitional period between childhood and adulthood whose cultural purpose is the preparation of children for adult roles.