The term Middle-earth has come to be applied as a short-hand for the entirety of Tolkien's legendarium, instead of the technically more appropriate, but lesser known terms Arda for the physical world and Eä for the physical reality of creation as a whole. This wider use is reflected in book titles such as The Complete Guide to Middle-earth, The Road to Middle-earth, The Atlas of Middle-earth, and the series The History of Middle-earth.