- Page_Load executes during every partial postback, same as regular postbacks.
- Use IsPostBack and IsInAsyncPostBack to avoid accidental execution of Page_Load code during partial postbacks.
- In conjunction with __doPostBack, __EVENTTARGET may be used to limit UpdatePanel life cycle event execution to only the targeted panel.
- Control events, such as Click and SelectedIndexChanged, fire after Load events.
By using PreRender instead of Load, you can allow control events to be handled before your code executes.