In this video Chris Pels shows how to control the criteria for caching an ASP.NET page based upon custom information. A sample page is created and then the OutputCache directive is used with the VaryByCustom attribute which contains a custom value. Next, the GetVaryCustomByString() method is overridden in the global.asax module which provides the handling of the custom attribute. In that method a string is returned that uniquely identifies the cached version of the page. Finally, there is a discussion about how caching using a custom value can be used in several ways for a web site.