That is because you normally have fast connection to proxy the server itself, or it is on your ISP's internal network.

There is only small delay that it going through server to get a new material off the Net. If the file is already in cache, you can save sending data over Internet entirely. Web users like to caching servers and they make the Web running much faster.

The web sites give benefit from caching servers, and a large organization ca set up Web site and download single copy of famous HTML page, it is rather then retrieving any identical copy for every person sitting behind corporate firewalls.

It is very difficult to tell the advertisers that single hit that you can get it fro American Online represent 100,000 readers. And it is easier to demand AOL stop caching, these sites have international copyright law on their sides.

Copyrighted documents stored in proxy serer cache are unauthorized copies. It tells caching proxy severs have previously cached out of date and there is also Pragma no cache header that tell the proxy not to cache information. A Web server could caching proxy and keeps the copy of Web page if proxy promised to turn and tell web server about number of hits received for the page over required time period. HTTP increased support for intelligent caching, header which lets proxy server to do something more intelligent with pages want to cache.