Discussion boards on websites normally detect and log your IP address when you post a message, which is not always desirable. Your IP address points directly to your Internet provider, and ultimately leads to you. Many webboards display this IP address to all visitors, so anybody on the Internet can get access to that information. Many participants of the casual and apparently anonymous discussions would think twice about what they say if they knew that it wouldn’t be difficult to find out who they are in real life and where they live.
As long as you are posting via a properly configured A4Proxy, however, your IP address is hidden from the site. All the site will be able to see is the IP address of the proxy server currently selected in A4Proxy. A4Proxy can also send to the site a completely fake IP address, confusing the site even further.