One way to improve the performance of any Web application is to cache static content in memory. Cached content is always returned faster than freshly rendered content. However, the tradeoff is that cached content may become stale. ASP.NET 1.x supports several kinds of caching, including:

• Page level: Each page may be cached as a whole piece or based on the parameters used to access the page. The cached page expires after a fixed time.

• Page fragment: If the page was built with user controls (.ascx files), then the user controls could be cached independently of the rest of the page content.

• Programmatic caching: The developer could also cache objects, thanks to the cache API. The cache API offers the distinct advantage of providing a means to create different types of dependencies for when the cache should be flushed.

In ASP.NET 2.0, the page level caching mechanism has been extended to support database dependencies. With a database cache-dependency, a cached page can be tied to a particular table in a SQL Server database. When the table changes, the cache will automatically expire.