**Every point on a number line corresponds to a unique real number.** A line is an infinite set of points and the set of real numbers is also infinite. Thus, there exists a one-to-one correspondence between the set of real numbers and the points on a number line.

A point is chosen on the number line as representing the real number 0. This point is called the origin on the number line. Points on the number line to the left of 0 represent negative real numbers. Points on the number line to the right of 0 represent positive real numbers. The distance between any two points on the number line is the same.