The rules which are used to determine what items are to be stored in a cache and how long they are to remain. For example, a Webmaster has to make a number of decisions about the cache which holds Web pages in a caching Web server. A typical decision is how long to keep pages in a cache before refreshing them by recopying them from their remote Web server. Another decision concerns which pages to cache: typically the Webmaster would ensure that any pages with a uniform resource locator which indicates that their server is close to the caching server would not be cached; he or she would also decide that very frequently accessed pages would be cached. All these decisions and many others form part of a caching policy.