J.R.R. Tolkien called the world containing Middle-earth and Aman Arda.
In Tolkien’s cosmology, Arda is the created world or realm in which the major events of his legendarium occur. Middle-earth is one of its principal regions, while Aman lies in the West and includes Valinor, the land associated with the Valar.
Arda exists within Eä, the wider created universe brought into being through the will of Eru Ilúvatar. This distinction matters because readers sometimes use “Middle-earth” for the entire setting, even though Tolkien’s mythology describes a broader world that includes lands beyond Middle-earth.
The name Endor is another source of confusion: Tolkien used it as a name for Middle-earth in some linguistic contexts. Valinor is only a region of Aman, so neither term names the whole world in the same way as Arda.