HttpContext.Current.Items - doesnt saved

 in my application i wrote HttpContext.Current.Items["bla"] = "blabla";
when i try get the value from another method i got the HttpContext.Current.Items["bla"] is null.
 
my question how the HttpContext.Current.Items saved?
does it like session + cache?
and the big question why the value dosent saved?
 
thanks!

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