Sitefinity CMS stores system objects that require intensive processing in the Application cache. Such objects can be configurations, localization resources, sitemap, users, taxonomy statistics, and so on. This way items are available globally (for example, the sitemap object is available from application cache on all pages that use navigation widgets, while the output cache of the page itself page is valid only for that page) and the optimal performance of the system is guaranteed.
Application cache is split into different sections depending on the objects it stores, and each section can have its own cache dependency, expiration, and storage location policies. Different objects and the respective application cache sections are managed by cache managers.
You can configure the default cache managers to control the behavior of the application cache, store your own objects in application cache via the default cache managers, or implement your own cache managers. For more information see: Administration: Configure Application cache.