plane and solid geometry, as described by euclid in his textbook elements is called "euclidean geometry". this was simply called "geometry" for centuries. in the 19th century, mathematicians created several new kinds of geometry that changed the rules of euclidean geometry. these and earlier kinds were called "non-euclidean" (not created by euclid). for example, hyperbolic geometry and elliptic geometry come from changing euclid's parallel postulate.