The book 13 Reasons Why by Jay Asher is about a teenage girl named Hannah who dies by suicide. Before her death, she records 13 cassette tapes explaining the 13 reasons for her decision, with each tape implicating a person who contributed to her decision. The main character Clay listens to all the tapes to understand why Hannah took her own life. The book explores the serious issue of bullying and its harmful effects on Hannah's mental health and wellbeing. It ultimately aims to bring more awareness to suicide prevention and the importance of treating all people with kindness, empathy and respect.