Spread is good way to get doubly enriched with Bonusy bukmacherskie i.e. the betting bonus. Spread is a way to intelligently bet on a weaker side expected to lose but yet manage to make money out of it. It is calculated as an advantage given in the form of some points to weaker team. The expected winner will have to win by a certain number of points. If you bet against the spread, you usually make an 11-10 bet. This means that you win $100 if you bet $110 for a total of $210 if your team covers the spread.
For a team to cover the spread, it will have to win by covering or bettering the spread margin. Suppose your bet is with Chicago, who is playing against a spread of Detroit with -5. It means Chicago will have to win by at least 6 points to cover the spread. Half-point spreads are also possible. But in case Chicago wins the game by 4 or fewer points, you lose the bet. In case Chicago wins the game by exactly 5 points, the bet is pushed. As the bet is pushed, the bettor i.e. you will receive the original amount of the bet back as if the stake was never placed.
There are sites in the Internet that offer serious spread betting bonus in capital market too. In fact, a few of them actually offer statistical model based guaranteed ROI also. Spread betting is believed more as an art than science by many. Professional betters usually have a strong spread betting portfolio. In case of betting bonuses or Bonusy bukmacherskie (a lucky term for me), a spread option is just right for you when you are matured and equipped well to handle the spread with quantitative precision. Never mind to consult an expert to guide you in this regard.