A pair of two numbers a and b listed in a specific order is called an ordered pair. The ordered pair (a, b) has a at the first place and b at the second place. To describe the location of a point, we use a definite order. That is,
(i) We start from the origin and first move along the x-axis. If the movement is to the right of the origin, the distance is taken as positive while the movement to the left of the origin gives the negative distance.
(ii) Then, we move along parallel to the y-axis. Again the distance above the x-axis is considered positive and that below it is considered as negative.