Euclidean geometry

Euclidean geometry is geometry of the type described originally by Euclid in his Elements (13 books written c.300 BC) and based on five axioms, one of which is the controversial parallel postulate.


Euclidean geometry is commonly split up into plane geometry, which is concerned with figures and constructions in two or less dimensions (such as the polygon, circle, ellipse, curve, line, and point), and solid or three-dimensional geometry, which deals with three-dimensional figures (such as the polyhedron, sphere, and ellipsoid).


Various forms of non-Euclidean geometry began to emerge in the 19th century, with enormous implications for science and philosophy.