In addition to the spread bet, a very common "side bet" on an event is the total (commonly called the over/under or O/U) bet. This is a bet on the total number of points scored by both teams. Suppose team A is playing team B and the total is set at 44.5 points. If the final score is team A 24, team B 17, the total is 41 and bettors who took the under will win. If the final score is team A 30, team B 31, the total is 61 and bettors who took the over will win. The total is popular because it allows gamblers to bet on their overall perception of the game (e.g., a high-scoring offensive show or a defensive battle) without needing to pick the actual winner.
A sharp bettor is viewed as a professional in the world of sports betting. Even the best bettors over time are not going to win more than in the mid-50 percent range, with general public losing more than they win. A sharp bettor is viewed as someone who has a proven record of success, and so when they place a bet on a game, a sportsbook will suspect they know something the general public might not. The point spread can change with a large amount of public money bet on a game, but it can also move with a smaller bet by sharps.

Placing a point spread bet means gambling on how much a team will win or lose by. In our above example, the Cowboys are the favorite. How do we know that? The minus symbol in front of the point spread indicates that the bookmaker thinks the final score will have Dallas winning by 7.5 points or more. The underdog, in our example that’s the New York Giants, will always be indicated with a plus sign. If you wager on the Cowboys on the point spread, America’s Team will have to win by at least 8 points for your wager to pay off. Should the Cowboys win by less than 8 points, your bet is lost.
Point Spread: The point spread remains the favorite way to wager on pro football, regardless of how many new forms of wagering come on stream. It’s called the line or spread and it’s known as betting ‘sides.’ The common misconception is that Las Vegas sets the spread as its best guess at the margin of victory. But really, it's a number they feel that is a perfect balance and will see an equal number of people to bet the underdog as on the favorite. A negative value like -6.5 means that team is favored by 6.5 points. So deduct 6.5 points from their total score. A positive value on the same game would be +6.5 (add 6.5 points to their final score) and would make that team an underdog of 6.5 points. The favorite must win by at least seven points to cover the spread. The underdog can lose by six points and still cover.