Euclid's postulates are a set of five postulates that describe Euclidian geometry. 1. * There exists a line that contains two points 2. * There exists a ray that contains two points 3. * One can draw a circle by picking a center point, and a distance 4. * All right angles (π∕2 radians) are congruent 5. * Given a straight line and a point, there exists one parallel line that passes through the point Some geometries, like hyperbolic geometry do not follow some, or all of these postulates.