In a pie chart the plot area is the colored circle in the center of the chart that is subdivided into wedges. The plot area of a pie chart represents a single data series
In addition to the series of data, the plot area also includes the chart's axes - such as the horizontal X axis and the vertical Y axis - the axis titles, gridlines, and data labels.
Plot Area and Worksheet Data
The plot area of a chart is dynamically linked to the data represented in the accompanying worksheet.
Clicking on the chart will typically outline the linked data in the worksheet with colored borders.
One effect of this linkage is that changes made to the data are also reflected in the chart making it easy to keep charts up to date.
In a pie chart for example, if a number in the worksheet is increased, the section of the pie chart representing that number will also increase.
In the case of line graphs and column charts additional data can be added to the chart by extending the colored borders of the linked data to include one or more additional series of data.