A query letter is a document that an author writes to pitch their book idea or manuscript to a literary agent, publisher, or editor. The purpose of this letter is to convince the recipient that the proposed work has potential and should be considered for publication or representation. A well-written query letter typically includes information about the book's genre, target audience, comparable titles, author credentials (if applicable), and a brief synopsis of the story or concept. The goal is to intrigue the reader enough to request either the full manuscript or additional materials such as sample chapters.