Assembly: System.Web (in System.Web.dll)
The SelectedIndexChanged event is raised when a different item is selected in a data listing control between posts to the server. The method allows you to create a custom handler for the event.
Raising an event invokes the event handler through a delegate. For more information, see Raising an Event.
The method also allows derived classes to handle the event without attaching a delegate. This is the preferred technique for handling the event in a derived class.Notes to Inheritors
When overriding in a derived class, be sure to call the base class's method so that registered delegates receive the event.