A proxy server is useful in a network with 5 or more machines. It's purpose is to reduce Internet traffic load (and therefore Internet usage costs) while increasing browsing speed by being a middle man for webpage requests. It works by caching each web request that comes in so when one user views a webpage that another user just visited rather than going out onto the Internet again to retrieve the requested page it will simply send the copy already downloaded and stored in its cache.
Frequently Asked Questions
Is there any reconfiguration required to use a proxy server?
Normally yes, you will need to specify a proxy server in your browser's settings. However you may wish to take advantage of a transparent proxy which is invisible to the clients.
Are there any drawbacks in using a proxy server?
No, to the user using a proxy server it is the same as browsing directly.