"Night World" is a series of young adult fantasy novels written by L.J. Smith. The series revolves around a hidden world where supernatural beings, such as vampires, witches, and shapeshifters, coexist with humans. Each book features different characters and storylines, exploring themes of love, friendship, and the struggle between good and evil. The series is set in a universe where the Night World operates under its own rules, and humans are largely unaware of its existence. The stories often highlight the challenges faced by characters who belong to both the human and supernatural realms, emphasizing their quests for identity and belonging.