pie chart

A pie chart (or a circle chart) is a circular  statistical graphic, which is divided into slices to illustrate numerical proportion. In a pie chart, the arc length  of each slice (and consequently its central angle and area), is proportional to the quantity it represents. While it is named for its resemblance to a pie                                                                                                              which has been sliced, there are variations on the way it can be presented. The earliest known pie chart is generally credited to William Playfair's Statistical Breviary of 1801.