A poster is a piece of printed matter used to promote or display a message. It usually contains images, text, and colors designed to attract the attention of the audience and convey the message. When inviting someone to write a novel, the poster could contain basic information about the novel, such as the novel's theme, genre, plot, and characters, as well as information about inviting the author to a conference or event to write the novel. The poster should also contain a clear contact information so that readers can contact the author and learn more.