Tag Mapping in ASP.NET

Tag mapping is using for mapping two controls of compatible type so that it'll map to the mapped control.Suppose we are creating a custom panel having some custom functionality like,

public class CustomPanel : Panel
{
    //Code here//
}

Now we can map all panels to our custom panel so that normal panel will get functionality of custom panel.In web.config,

<pages>
 <tagMapping>  
    <clear />  
    <add tagType="System.Web.UI.WebControls.Panel"
                mappedTagType="CustomPanel"/>
 </tagMapping>
</pages>