Four Postulats of Euclides

Postulat I
For every point P and for every point Q not equal to P there exists a unique line l that passes through P and Q.
Postulate II
For every segment AB and for every segment CD there exists a unique point E such that B is between A and E and segment CD is congruent to segment BE.
Postulate III
For every point O and every point A not equal to O there exist a circle with center O and radius OA.
Postulate IV
All right angles are congruent to each other.

The fifth postulate is really the most one
Greenberg, M.J., 1973, “Euclidean and Non-Euclidean Geometries: Development and History”, San Francisco: W.H. FREEMAN AND COMPANY