[Description] If the request is a postback, control event handlers are called. After that, the Validate method of all validator controls is called, which sets the IsValid property of individual validator controls and of the page. (There is an exception to this sequence: the handler for the event that caused validation is called after validation.) [Stage] 
Postback event handling
P a g e r e q u e s t
S t a r t
I n i t i a l i z a t i o n
L o a d
P o s t b a c k e v e n t h a n d l i n g
R e n d e r i n g
U n l o a d