Proxy addresses are for those who want to browse the Internet without showing their true identity. There are many reasons why someone would want to hide their identity on the Internet.
When you use a proxy address, your computer connects to the server using its true IP address (its identity, in other words). From that moment, whatever information you send is sent to the destination server using the address of the proxy in place of yours.
To connect to a website, your computer must send a special connection request to the proxy server telling it to connect to that particular website. The proxy server then relays negotiation data back and forth between your computer and the final destination with which you want to communicate.
A proxy server provides a plausible solution for someone who wants complete privacy. Your IP will not be involved in any transaction between you and the host to which you want to talk, making the server completely unaware of your presence.
Proxy communication is relatively slow, especially on public proxy servers. Not only that, but some websites do not allow proxies to connect to them.
Where to Find Proxies
The best place to start looking for proxies is in a public proxy list.