Area charts emphasize the volume of data, from the baseline of a chart to the top of a trend line.

There are 2 types, cumulative and stacked.

• Cumulative consists of lines on a multiline chart with the areas beneath each line shaded. Each line is measured from the baseline.
• Stacked also shows several data sets, but each area is measured from last area. Areas do not share a common baseline. Because they don’t share a baseline, order of the areas can radically affect the look and meaning of the chart.

The area that is to be emphasized needs to be placed along the baseline. There it is most prominent and easiest to judge the size of the area with the flat baseline. The smoothest band (one with the least variation) can also be placed at the bottom of the chart and so on up to the top.