Charts are very much useful to visually present the data. In Reporting applications these are very much useful to present huge amount of data.
Before ASP.NET 4.0, to show Chart control in web page, users often resorted to Microsoft OWC chart control or some private controls.
ASP.NET 4.0 came up with Chart Control, which makes presenting data in chart in a web page makes very easier. Presenting data in chart is very easy.