Chart is a graphical representation of statistical data. Different types of data require different types of charts in order to provide a meaningful representation. Some common charts are line chart, bar chart, histogram and pie chart.

Pie chart is a circular chart cut into different sectors. It is used to describe ratio of categories. The area of each sector represents the percentage share of the corresponding category. It is always difficult to compare the areas among different sectors, so a common practice is to label each sectors with percentages.