Notes for Introduction to Graphs

The purpose of drawing a graph is to show numerical facts in usual form so that they can be understood quickly, easily and clearly. We also know that a bar graph is used to show a comparison among categories. A bar graph may consists of two or more parallel horizontal or vertical bars of equal width.

A pie-graph is used to compare various parts of a whole using a circle. A histogram is a bar-graph that shows data in intervals. It has adjacent bars over the intervals as shown below.

A line-graph is called a linear-graph and it displays data that changes continuously over periods of time.