ASP.NET caching stores frequently accessed data or whole webpages in memory, where they can be retrieved faster than they could be from a file or database.Stored at Server ,Page Level and Application Level , This causes the cache to be invalidated so that the page is dynamically generated.Page output caching stores a copy of a rendered page (or user control) in the server’s memory. Subsequent requests for the resources are served from memory. Page output caching practically eliminates rendering time.