ASP.NET server controls such as the Repeater, DataList and GridView Web controls can contain child controls that raise events. For example, each row in a GridView control can contain one or more buttons created dynamically by templates. Rather than each button raising an event individually, events from the nested controls are "bubbled"—that is, they are sent to the control's parent. The parent in turn raises a generic event called RowCommand with parameter values. These values allow you to determine which individual control that raised the original event. By responding to this single event, you can avoid having to write individual event-handling methods for child controls.
While you cannot override this method, controls you author can handle or raise bubbled events by overriding the OnBubbleEvent method.