Middle-earth is the main setting of J.R.R. Tolkien’s The Lord of the Rings.
Tolkien used Middle-earth as the English rendering of a name for the inhabited world in his mythology. It is not the name of an entire separate planet; it refers to a region of Arda, the world created within Tolkien’s legendarium. The major story locations include the Shire, Rivendell, Gondor, Mordor, and Rohan.
The term is often used broadly for Tolkien’s interconnected mythology, but the geography changes across different ages. The Lord of the Rings takes place near the end of the Third Age, while The Silmarillion focuses largely on events from earlier ages. Narnia and Earthsea belong to other authors’ fantasy worlds.