The Composition Composition is a structured essay (composition) that informes the reader about the structure/make-up/formation (composition) of something.  The purpose is twofold:  first, to give you a chance to learn more about something and share that knowledge with your readers; and second, to have you gain appreciation of a recipe-style writing process.  The topic has to be simple enough to be adequately described in one page and it should not be a process that you describe (this is not a how-to essay).