Betting lines display the odds that a bet will pay out in a game. The odds are adjusted by the sportsbook throughout the week to reflect current betting action and market conditions. They also change after information is released that could affect the game.
For example, if an injury is announced that affects the perceived talent of a team, the line will move to reflect this. The lines are also adjusted to encourage action on both sides of the wager. This is done to even the playing field for both teams and to attract a larger amount of bettors to each side.
In the above example, the Celtics are -2 underdogs against the Jets, which is a +7 point spread. This means the favorite must win by at least 8 points to cover the spread, while a loss by 7 or less wins the bet (a push). The +7 point also indicates that it is unlikely that the underdog will lose by more than 7.
Money lines (e.g. Eagles -770) work differently as they show how much you would earn on a $100 bet. Negative numbers indicate how much you must risk to win $100 and positive ones tell you how much you would make.
Totals (over/under) also move after the initial release of the lines. They are based on the total number of points or goals scored in a game and you bet on whether the final score will be higher or lower than the set number. You can also “middle” a total by betting on both the over and under, so long as you don’t bet more than $100.