The RowCommand event is raised when a button within the GridView control is clicked. This allows you to provide an event-handling method that performs a custom routine whenever this event occurs.
The GridView control also raises other specialized events when certain buttons are clicked (buttons with the CommandName property set to "Delete", "Update", and "Page" for example). When using one of these buttons, you should consider handling one of the specialized events provided by the control (such as RowDeleted or RowDeleting).
When you create a GridViewCommandEventHandler delegate, you identify the method that will handle the event. To associate the event with your event handler, add an instance of the delegate to the event. The event handler is called whenever the event occurs, unless you remove the delegate. For more information about event-handler delegates, see Events and Delegates.