[Vicez]

There are two different method, the arbitrage and the matched betting.
They are similiar but the arbitrage is exploit the quote on various betting site in order to have mathematical gain on every bet, the matched betting i think its a way to earn some money from the betting site free bonus.
I would suggest you to watch only site from your country because every country has some law for betting.
For example i know that in many country if a bookmaker suspect that you are using their website for arbitrage they could suspend your account and freeze the money in it.