[Description] The page request occurs before the page life cycle begins. When the page is requested by a user, ASP.NET determines whether the page needs to be parsed and compiled (therefore beginning the life of a page), or whether a cached version of the page can be sent in response without running the page. [Stage] 
Page request
P a g e r e q u e s t
S t a r t
P a g e i n i t i a l i z a t i o n
L o a d
V a l i d a t i o n
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