Caching is defined as temporary storage of data for faster retrieval on subsequent requests. In ASP .NET 2.0, the caching support is integrated with the DataSource controls to cache data in a web page. ASP.NET 2.0 also now includes automatic database server cache invalidation. This powerful and easy-to-use feature allows developers to aggressively output cache database-driven page and partial page content within a site, and have ASP.NET automatically invalidate these cache entries and refresh the content whenever the back-end database changes. ASP .NET 2.0 also introduces the Substitution control, which allows you to link dynamic and cached content in a web page.