A statement that is accepted as true without proof.
Through any 2 points there is exactly 1 line
Through any 3 non-collinear points there is exactly 1 plane.
If 2 points lie in a plane, then the line containing those points lies in the plane.
If 2 lines intersect, then they intersect in exactly one point
If 2 planes intersect, then they intersect in exactly one line.
The points on a line can be put into a 1 to 1 corespondence with the real numbers.