Web browsers and web proxy servers employ web caches to store previous responses from web servers, such as web pages and images. Web caches reduce the amount of information that needs to be transmitted across the network, as information previously stored in the cache can often be re-used. This reduces bandwidth and processing requirements of the web server, and helps to improve responsiveness for users of the web.
Web browsers employ a built-in web cache, but some internet service providers or organizations also use a caching proxy server, which is a web cache that is shared among all users of that network.

To clear cache in Safari in Mac OS X Mountain Lion:

1. Enable Developer Menu by clicking last checkbox in last tab in Safari/Preferences.
2. Click Developer Menu/Clear caches or Press Alt+Cmd+E

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