A watermark is a recognizable image or pattern embedded into paper or digital content, primarily used to signify ownership or copyright. In the context of children's books, watermarks serve to deter unauthorized reproduction or distribution of illustrations and text. They can be a logo, name, or a subtle design, intricately placed so it doesn't interfere with the overall visual experience, yet remains identifiable. Watermarks are particularly important in protecting creative works in an industry where images and stories frequently cross paths.