I think it has been related to caching concept but don't know how is it used.
+1
A:
You can read about page output caching on MSDN: http://msdn.microsoft.com/en-us/library/ms178597.aspx
The directive allows you to specify settings such as whether a page should have its output cached, for how long, and other configuration options.
Output caching can be a performance benefit to a page that is expensive to run. Once it is cached, future requests will be served from the cache without the page having to run again.
Eilon
2010-07-06 04:40:46
Dont forget you can also specify OutputCache for a user control. Im sure you know already, just thought id mention so OP knows.
RPM1984
2010-07-06 04:52:46