Worldbuilding is the process of constructing an imaginary world, sometimes associated with a whole fictional universe. The term "world building" appeared as early as 1965 in science fiction criticism, and is used in relation to science-fiction or fantasy stories and games. The resulting world may be called a constructed world. Developing an imaginary setting with coherent qualities such as a history, geography, and ecology is a key task for many science fiction or fantasy writers. Worldbuilding often involves the creation of maps, a backstory, and people for the world. Constructed worlds can enrich the backstory and history of fictional works, and it is not uncommon for authors to revise their constructed worlds while completing its associated work. Constructed worlds can be created for personal amusement and mental exercise, or for specific creative endeavors such as novels, video games, or role-playing games.