https://msdn.microsoft.com/en-us/library/ms178472%28v=vs.85%29.aspx

http://www.c-sharpcorner.com/UploadFile/deveshomar/page-life-cycle-between-content-page-aspx-page-and-user-co/

http://msdn.microsoft.com/en-us/library/ms178472%28v=vs.100%29.aspx

Go to this link.. http://www.tutorialspoint.com/asp.net/asp.net_life_cycle.htm