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Proxies are store-and-forward caches. When you configure your web browser to use a proxy, it never connects to the URL. Instead, it always connects to the proxy server, and asks it to get the URL for you. Proxies can be used as a sort of firewall, because it isolates you from connecting to the Internet.

How does a proxy server work?

A proxy server receives a request for an Internet service (such as a Web page request) from a user. If it passes filtering requirements, the proxy server, assuming it is also a cache server, looks in its local cache of previously downloaded Web pages. If it finds the page, it returns it to the user without needing to forward the request to the Internet. If the page is not in the cache, the proxy server, acting as a client on behalf of the user, uses one of its own IP addresses to request the page from the server out on the Internet. When the page is returned, the proxy server relates it to the original request and forwards it on to the user.

To the user, the proxy server is invisible; all Internet requests and returned responses appear to be directly with the addressed Internet server. (The proxy is not quite invisible; its IP address has to be specified as a configuration option to the browser or other protocol program.)

What are the advantages of using a proxy server?

An advantage of using a proxy server is that its cache can serve all users. If one or more Internet sites are frequently requested, these are likely to be in the proxy's cache, which will improve user response time. In fact, there are special servers called cache servers.

The functions of proxy, firewall, and caching can be in separate server programs or combined in a single package. Different server programs can be in different computers. For example, a proxy server may in the same machine with a firewall server or it may be on a separate server and forward requests through the firewall.

There are different types of proxy servers with different features; some are anonymous proxies, which are used to hide your real IP address and some are used to filter sites, which contain material that may be unsuitable for people to view.

When you connect to a web site, your true IP address will not be shown, but the proxy server's IP will. This does not mean that you're completely anonymous. The proxy server will have logs of IP’s that used the proxy server and the times.

So why should you use a proxy?

You can use a proxy server if you have a child and wish to restrict the sites they are viewing. You will need to make sure you get the correct type of proxy because not all proxies filter sites. You can use it to protect yourself, it can be used to hide your IP, which is useful because it means hackers can not get info about you when using it. They will only get the proxy server's IP. Proxy servers are not hard to set up, no hardware or software is needed, you just need to configure your browser to connect through it.

Some ISP’s (Internet Service Providers) make all their users use a proxy server; for example in the United Arab Emirates, the main ISP makes all users use a proxy server which blocks sites with unsuitable material. It does this using the meta tags in the HTML code used to make the web page. Some ISP’s may give you a choice so you can use one or not. If you want to use a proxy server there are many around with different functions, you just have to get the one that suits your needs best.