Editing World Wide Web (section)

=== Caching ===
A [[web cache]] is a server computer located either on the public Internet or within an enterprise that stores recently accessed web pages to improve response time for users when the same content is requested within a certain time after the original request. Most web browsers also implement a [[browser cache]] by writing recently obtained data to a local data storage device. HTTP requests by a browser may ask only for data that has changed since the last access. Web pages and resources may contain expiration information to control caching to secure sensitive data, such as in [[online banking]], or to facilitate frequently updated sites, such as news media. Even sites with highly dynamic content may permit basic resources to be refreshed only occasionally. Web site designers find it worthwhile to collate resources such as CSS data and JavaScript into a few site-wide files so that they can be cached efficiently. Enterprise [[Firewall (networking)|firewalls]] often cache Web resources requested by one user for the benefit of many users. Some [[search engines]] store cached content of frequently accessed websites.