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.

Léon Lalanne later used a polar diagram to show the frequency of wind directions around compass points in 1843. The circle in the centre represents the root node, with the hierarchy moving outward from the center.

The use of superfluous dimensions not used to display the data of interest is discouraged for charts in general, not only for pie charts.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.Similar to basic circular pie charts, square pie charts take each percentage out of a total 100%.The following example chart is based on preliminary results of the election for the European Parliament in 2004.