What is proxy server?
This is taken from wikipedia.
In computer networks, a proxy server is a server (a computer system or an application program) that acts as an intermediary for requests from clients seeking resources from other servers. A client connects to the proxy server, requesting some service, such as a file, connection, web page, or other resource, available from a different server.
To understand how it works,you can refer this picture
function in travian.
As in travian,multihunter can detect that you play multiple account easily if both of your account are using same ip address(means it come from 1 pc). You can use the function of proxy server to overcome this situation. There are lots of proxy server that available in internet for you to use. One of them is publicproxyservers.com. using this web proxy, you can use multiple account in one browser under one roof. You also can search for the other proxy,,if you too lazy for this i can help you. just click this. You might found lots of proxy server web that can be used if you wish to play multi account in travian without being caught easily.
You also might try this proxy. This is one my favorite proxy website because its fast and you can play happily without pop out ads.
p/s: i also know how to make all your account working with greasemonkey and travian beyond. stay tuned for more from me.
UPDATE: I'VE CREATED A TUTORIAL ON HOW TO CHANGE YOUR PROXY DIRECT IN YOUR FIREFOX, YOU CAN CHECK IT HERE.