SOCKS is a protocol that is intended to act a circuit level proxy for applications. It is very different from ‘normal’ proxy because they are application proxies. For example, when you use a HTTP proxy you are actually forwarding the HTTP request, and the HTTP proxy server then performs the request on your behalf. An example of this would be asking someone to pass you the salt at the dinner table, who then gets the salt shaker, and passes it to you.
The purpose of carders using proxy servers (Socks) is to conceal the users identity, or to spoof a certain geo-location (so for example hackers in London, UK spoof his location as web browser showing he is in New York, USA so he can cashout USA victim's bank account).