A pie chart, also called a pie graph, is a circular graph often used to represent percentages. William Playfair invented the pie chart in 1801.
A pie chart takes the form of a circle that is divided into sections that resemble slices of a pie. The size of each section, or slice, is proportional to the percentage or fraction that it represents. An exploded pie chart shows the segments, or slices, of the circle as slightly separated from the circle's centre. This is used for emphasis
A proportional pie chart is often used for business reports and can easily display financial data at a glance. Although the pie chart has been embraced by many, some believe that the pie chart is not as accurate at displaying exact numbers the way line length in a graph does.
The pie chart can be a simple and effective way to visually represent data. It is useful in showing how one section relates to the whole. Pie charts are also more simple and easier to understand than many other graphs and in many cases are self-explanatory.