RadChart has been replaced by RadHtmlChart, Telerik's client-side charting component. If you are considering RadChart for new development, examine the RadHtmlChart documentation and online demos first to see if it will fit your development needs. If you are already using RadChart in your projects, you can migrate to RadHtmlChart by following these articles: Migrating Series, Migrating Axes, Migrating Date Axes, Migrating Databinding, Features parity. Support for RadChart is discontinued as of Q3 2014, but the control will remain in the assembly so it can still be used. We encourage you to use RadHtmlChart for new development.
PlotArea MarkedZones are ranges that can be labeled and filled to highlight areas of the chart or to visually group data. The MarkedZones property by default display behind the chart series. You can create any number of members for the MarkedZones collection and each marked zone is defined by a starting and ending X and Y value pairs. You can also control the labelling and appearance for each zone independently.