What is it about diaries?

People say you feel better about stuff when you write it down. It's like having a private conversation with yourself. You can tell a diary private things, secret stuff that no one else knows. That's the sort of relationship Soph has with her diary, alone in her bedroom, late at night. She writes about her best friends, Mel and Kate, her problem parents, boys, sex, school and all the things that are on her mind.