Each presentation component may generate different output under different conditions. For example, a footer rendering might generate the same output for all pages, while a breadcrumb rendering may generate different output for different URLs, and a navigation rendering might generate different output for different users based on their access rights to content items. The layout engine can cache the output of each sublayout and rendering used by each page view. Developers use rendered output caching to improve performance by not executing sublayouts and renderings under different conditions, instead retrieving output generated previously by that component under the same conditions. While output caching does not eliminate the need for data structure and code optimization, avoiding code execution can increase performance significantly, especially in high-volume solutions. Page caching, such as by using the OutputCache directing in an ASP.NET Web form, can consume excess memory a component generates the same output for numerous page views. Page caching does not support dynamic features. Sitecore component output caching allows the output of each component to vary by a number of criteria as described in the following sections, caching only when appropriate.