During the life cycle of an ASP.NET page, the Page object exposes some frequently used standard events. When the ASP.NET page framework runs, it automatically connects (wires) to the corresponding proxy instances for these methods. This way you don't have to write the necessary "glue code". The following list provides runtime wired agent instances in order of firing:
• Page_Init: During this event, you can initialize values or connect any event handlers you may have.
• Page_Load: During this event, you can perform a series of actions to create an ASP.NET page for the first time or respond to client-side events caused by delivery. Before this event, the page and control view state had been restored. Use the IsPostBack page property to check whether this is the first time the page is being processed. If this is the first time processing, perform data binding. Additionally, read and update the control properties.
• Page_DataBind: When the DataBind method is called at the page level, the DataBind event is raised. If you call DataBind on a single control, it only fires the DataBind event of the control below it.
• Page_PreRender: Fires the PreRender event just before saving the view state and rendering the control. You can use this event to perform all last-minute operations on the control.
• Page_Unload: After page rendering is complete, the Page_Unload event is fired. This event is a good place to perform final cleanup work. This includes operations such as cleaning open database connections, discarding objects, or closing open files.
The following list summarizes non-deterministic events. • Page_Error: The Error event is fired if an unhandled exception occurs during page processing. Error events provide you with the opportunity to handle errors gracefully.
• Page_AbortTransaction: Transaction events are useful if you want to indicate whether a transaction succeeded or failed. This event is typically used in shopping cart scenarios where this event can indicate whether the order was successful or failed. This event is fired if the transaction has been terminated.
• Page_CommitTransaction: This event is fired if the transaction was successfully committed.
http://www.cnblogs.com/hide0511/archive/2006/08/30/490783.html