Assembly: System.Web (in system.web.dll)
When notified by this method, Web server controls must perform any initialization steps that are required to create and set up an instance. In this stage of the server control's life cycle, the control's View state has yet to be populated. Additionally, you cannot access other server controls when this method is called, regardless of whether it is a child or parent to this control. Other server controls are not guaranteed to be created and ready for access.
Raising an event invokes the event handler through a delegate. For more information, see Raising an Event.
The OnInit 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 OnInit in a derived class, be sure to call the base class's OnInit method so that registered delegates receive the event.