Remember that every spread still has a moneyline attached to it. While that might be a bit confusing, all that refers to is the cost of betting the spread; not how the outcome will be decided. For example, if someone says to you that “the Patriots are laying three points but I have low juice, so my moneyline is -104”, what they are referring to is the price of betting the spread. That merely means that they are betting the spread but the moneyline attached to betting that spread is -104.
These are the point spread bets available for three preseason NFL football games. Let's start by identifying all of the elements of these bets so that you know what you're looking at. The first column is the two teams that are competing. This should be pretty straightforward. The next thing you will see is a plus or minus sign on each team's line. Teams with a minus sign in front of the number are the favorites and teams with the plus signs are the underdogs. In the above examples, the Chiefs, Seahawks, and Chargers are all the favorites. The Bengals, Broncos, and Cowboys are all underdogs.
The favorite team or player on the moneyline is the team that’s expected to win. This side of the bet usually listed with a minus (-) sign. The underdog team or player on the moneyline is the team that’s expected to lose. This side of the moneyline is usually listed with a plus (+) sign. These signs signify how either side of the wager will pay. The minus side will pay less than original wager while the plus side will pay more than the original wager.
The point spread bet is a bet designed to give each team an equal chance of winning a particular game. Obviously, not all teams are equal, so the sports-books have devised a mechanism to even up the teams, and that is by taking points/runs/goals off the team who is favored. The more a team is favored, the more the gambling site will take off them, enough to theoretically make the game a 50/50 chance.

To show how this can be exploited, take a point spread of -8.5 at odds of -110. This is a 50/50 proposition. Let's assume you've purchased enough points to move the spread to -6.5 at odds of -150. Now, you'd win instead of lose 6.24% of the time they win by 8, and 6.59% of the time they win by 7. Add these together with the 50% from the original proposition, and we get 62.83%.
In theory, sportsbooks don't care about the outcome of a game, although for those of you who bet on the Steelers (-5.5) last season versus the Chargers and saw a game winning TD  returned by S Troy Palumalu as the game expired reversed, thus negating a seven point victory and putting the final at 11-10, you might think otherwise, but this is how it's supposed to be.
The point spread, which is sometimes referred to as the “handicap”, is the number of points taken from the favorite, or given to the underdog, in order to open up the chances of either team winning the wager evenly. In most games, there’s usually a team that is more likely to win, based on a number of statistical factors. If the only kind of wager available was on who would win between a very strong team and a poor team, it wouldn’t be all that exciting. The point spread was designed to make betting much more interesting, since it allows a bet on the losing team to win you money. How? Let’s break down an example: