Betting arbitrage (“miraclebets”,”surebets”, sports arbitrage) is an example of arbitrage arising on gambling markets due to either bookmakers’ differing opinions on event results or errors. When conditions permit, by putting one bet per each outcome with different betting companies, the bettor may create a profit whatever the outcome. Mathematically arbitrage happens when there are a set of chances, which represent all mutually exclusive outcomes that cover all state space possibilities (i.e. all outcomes) of an event, whose implied probabilities add up to less than 1.  In the bettors’ slang an arbitrage is frequently known as an arb; individuals who use arbitrage are known as arbers. 
Arbitrage betting involves relatively large sums of money, provided that 98% of arbitrage opportunities return less than 1.2 percent.  The practice is generally detected quickly by bookmakers, who typically hold an unfavorable view of itand this can lead to half of an arbitrage bet being canceled. Arbitrage betting is always insufficiently profitable due to detection, unreliable gambling websites, limiting of stakes, hackers, and scammers which use high percentage arbitrages to deceive bettors into providing security credentials. [citation ]
Bookmakers generally disapprove of gambling arbitrage, and restrict or close the accounts of people who they suspect of participating in arbitrage betting.  Although arbitrage gambling has been around since the beginnings of bookmaking, the rise of the Internet, odds-comparison sites and betting exchanges have made the practice simpler to perform. On the flip side, these changes also made it simpler for bookmakers to keep their chances in accord with the market, since arbitrage bettors are essentially acting as market makers.
In Britain, a practice has developed in which exceptionally seasoned”key men” employ others to place bets on their behalf, so as to avoid detection and increase access to retail bookmakers and allow the financiers or key arbitragers to stay in a computer to keep track of market movement.
Arbitrage is a very fast-paced procedure and its successful operation requires a lot of time, expertise, dedication and discipline, and especially liquidity.