In the world of betting the "SureBet" are well know.

The surebet are a special way to bet, also know as sports arbitrage, using the difference in prices between the many sportsbooks that populate internet creates a gain "safe".

For simplicity, we see an example

In the match Roma - Milan where

If we use the difference of quote between the bookmaker1 and bookmaker2 dividing our stake correctly in a timely manner our bet, for example of 100€ we have: 49.02 on home team of book1 28.60 on draw "X" of book2 and 22.38 on away team "2" of book2 for a winning total of 102.95€. So in essence we won €2.95 no risk. This is the theoretical part, now some considerations:

1. There are sites that compare the odds of different bookmakers helping you to find surebet, a good site is: betbrain, it has a "free" version with a delay of 15 min and one to payment with no delay, in real time.
2. The bookmakers when they see these differences, quickly corrected odds, so you will be timely in placing your bets
3. Bookmakers have in their rules the clause to cancel your bet in case of obvous error, such as in in the case of reversal odds between favorite and underdog team, in this case you risk of having a single matched bet, with the consequences that immaggine
4. To most of the bookmakers do not like the professional players, so you can easily find with your accounts closed or restricted to very low maximum bets also less than 10 eur (check our bookmakers reviews to know the bookmakers that accepted the professional players)

All this explains that sports arbitrage exist and can be fun as a hobby but to make a profession is not easy it takes much time and experience.