A chart sheet is a worksheet in a workbook that has its own sheet name. These are employed to give a clearer view when using a large chart with a large data. The chart is linked to worksheet data and is updated automatically when there are changes. The IChart interface is the in-memory representation of the chart worksheet in an Excel workbook. These are used to create charts and to set properties for those charts. The IChartSerie interface can be used to set various formats for a series.