Mathematics-Bar Graph

Bar Graph is the way of summarizing the set of particular data ( categorical data ). It displays the data using bars of same width. The height of the bar is proportional to sum of the values of categorical data.

The bars can be plotted vertically or horizontally. It is used for visual representation of categorical data. Categorical data is grouping of data into discrete groups, such as months of a year, states of country, age group etc.

The categories appears along the horizontal axis. 2 types of bar charts are available. Grouped bar charts and stacked bar charts.

In grouped bar chart, each  categorical group there are 2 or more bars. In stacked bar chart, stack bars that represent different bars on top of each other. The height of bars shows combined result of groups.

The first bar graph apperaed in William Playfair's book 'The Commercial and Political Atlas'.