Earlier, we explained how the implied probability of -240 is 70.59% and how the implied probability of +210 is 32.36%. Notice these two probabilities total 102.95%. The extra 2.95% is the bookmaker's advantage. It's called vig, and it's basically a commission that they charge customers for placing wagers. By removing the vig, you can see what the fair odds on the game would be.
In this example the Jets are listed as four-point favorites (-4) over the Bills and the 49ers are three-point underdogs (+3) against the Seahawks. So, if you bet $110 on the favored Jets, they must defeat the Bills by more than four points in order to win $100. If you bet $110 on the underdog 49ers you will win $100 if they win outright or lose by less than the three-point spread. If the final score happens to end up exactly on the number it's a tie, or 'push,' and you get your money back.

Let’s start with the basics: what do sports bettors mean when they talk about a ‘line?’ The word line, in the language of a sportsbook, can refer to either the odds and/or a point spread in any sports contest. Let’s take a look at an imaginary line the way you’d read it off the board sitting in a Vegas sports betting lounge or on the screen at your online book. Let’s imagine a game between the New York Giants and the Dallas Cowboys. Your book’s NFL betting line might look something like this:

The one variance you might come across in any pointspread listing is the commission owed on a bet. Instead of moving the actual spread for a game, some books will try and direct money one way or the other by adjusting the juice. For example, if there was a (-120) next to the listed pointspread, you would now owe $120 on a losing $100 bet. Sometimes a book will reduce or eliminate the juice all together to move money towards a particular side of a matchup. In this case, you might see (-105) or (+100) next to the pointspread to signify the reduced or zero commission for that bet.

We went into detail earlier about what causes moneylines to move. The better you can get about predicting when these movements will occur and in what direction, the more profitable you’re going to be as a sports bettor. If you find a bet that you like, but you predict it’s going to move more in your favor, you can intelligently wait to bet and lock up a potentially much more profitable opportunity.
Almost all point spread wagers are paid out at moneyline odds of -110. This is almost even money minus the percentage that is taken for the sportsbook's cut known as the vig. Sometimes you will see a bit of variation in the payout odds, but for the most part, you should expect to see -110. If you don't see the payout numbers posted but just the point spread, you can most likely assume that you are to interpret that as being paid out at -110. If you're ever curious, though, just ask for clarification or look at your betting slip.
Obviously, the first three letters on the top two lines of the three-line package of symbols represents a team in the game you’re wagering on; NYG stands for the New York Giants, while DAL stands for the Dallas Cowboys. The number next to each team’s name is known as the spread or the point spread. Wagers on the point spread are among the most popular sports wagers in the world. The reason this wager is popular is that it doesn’t matter which team wins or loses; what matters is the amount of points the teams score, and whether or not the team you place your money on beats the difference in points (the ‘spread’) or not.
Where people seem to get confused with moneyline bets is with how they are presented and how they pay out. While the criteria to win a moneyline bet will never change, the amount you win and how the bet is presented will change. Don’t worry, though. It’s easy to understand if it’s presented to you properly. We are going to cover this thoroughly in the coming sections. You’ll be a moneyline expert ready to crush the books when you get done with this guide.
We're often asked a question along the lines of "why would I place moneyline wagers rather than point spread wagers?" There's no simple answer to this question really, as point spreads and moneylines shouldn't be viewed as "either/or" options as such. You don't have to decide that you're always going to bet on the spread, or that you're always going to bet moneylines. These are two different wager types that have their own merits, and any bettor should have them both in their arsenal.
That was all before Charles McNeil, a math teacher from Chicago, invented the concept of the point spread. An avid gambler, McNeil created what he called “wholesaling odds” and started his own bookmaking operation in the 1940s. He started out offering this new style of betting on football, but his business model grew to include basketball.  McNeil changed the way sports betting was done, and his legacy lives on today in what we now call the point spread.