Pictorial Representation of Graph:

A graph is a pictorial representation of the relationship among two or more physical quantities. Graphs are used often both to present fundamental data on the behavior of physical systems and to monitor the operation of such systems.  The basic principle of any graph is which distances are used to represent the magnitudes of numbers.  The number line is the easiest type of graph. Those all numbers are represented as distances along the line.  Positive numbers are situated to the right of zero, and negative numbers are situated to the left of zero.

The coordinate system of a graph is the framework upon that the graph is drawn.  The coordinate system consists of numbered scales which provide the base and the direction for measuring points on the graph.  Any point on a graph can be specified through giving its coordinates.  Coordinates elaborates the location of the point with respect to the scales of the coordinate system.  There are various different coordinate systems generally encountered.