Ans. Caching is a technique of storing an in-memory copy of important and much used data/information to improve the performance of any software system. The idea is to place frequently used data in quickly accessed media. The ASP.Net runtime includes a key-value map of CLR objects called cache. This lives with the application and is available via the HttpContext and System.Web.UI.Page. Using cache is to some extent similar to using Session object. You can access items in the cache using an indexer and may control the lifetime of objects in the cache and set up links between the cached objects and their physical sources.