The novels are set on the Discworld, a flat world balanced on the backs of four elephants which, in turn, stand on the back of a giant turtle, Great A'Tuin. The books frequently parody, or at least borrow ideas from, J. R. R. Tolkien, Robert E. Howard, H. P. Lovecraft and William Shakespeare, as well as mythology, folklore and fairy tales, often using them for satirical parallels with current cultural, technological and scientific issues.