A -10 on a betting line can apply to a variety of sports and means you are wagering on what's known as the spread. A spread is the designated number the oddsmakers have set for the final margin of points between the two teams.
If an NFL team, for instance, is listed as listed as -10, it is giving away 10 points and is considered the favorite. This means for it to cover a bet it must win the game by 11 or more points. A team listed at +10 is the underdog and will produce a winning bet if it loses by less nine points or less. The team at +10 is also a winning bet if it pulls an upset and actually wins the game.
Some games can also appear as a pick'em, which means the oddsmakers have decided the teams are basically even. When this happens you are being asked to basically wager on what's known as a moneyline bet. In a moneyline bet, you are simply picking which team you think will win the game and has nothing to do with the spread.
In an effort to avoid games ending up with the same final score as the spread, bookmakers will add a .5 to the spread line. This guarantees bets will produce winners and losers and won't result in a wager that ends up in a tie or, in gambling language, what's called a push. Should an NFL game be listed at -10 and the final score is 20-10, bettors will be refunded their money no matter which team they picked to cover the spread.
Gamblers should remember that the aim of a sportsbook is to have an equal amount of money come down on both teams. As a result, you might see the -10 go up and down in an effort to balance the amount of money being wagered on each team. The odds can also change when bookmakers are trying to draw equal action on each team. If a favored team is listed at -110 on a moneyline bet, this might change to -120. As a result, instead of betting $110 to win $100, you would need to bet $120 to win $100.