Describe the exposition of The Perks of Being a Wallflower

In the novel's exposition, fifteen-year old Charlie is struggling to cope with the death of his best friend, Michael. Charlie writes letters to a stranger in order to cope with his anxiety and to put his struggle into words. High school is difficult to navigate even when surrounded by friends, but for Charlie, the loss of Michael leaves his to face this new experience alone. In the beginning, the other students make fun of Charlie because he is so smart. Over time, however, he finds support from his English teacher, Bill, and he makes new friends.... with Sam and Patrick.