Sports wagering has boomed with the advent of the Internet, as easily evidenced by the hundreds of Web sites willing and able to take action. If you're looking to get in on this growing past time, it pays (literally) to know what you're doing. Therefore we bring you this basic betting primer, a "Sports Betting for Dummies."

Point Spreads and Money Lines

Inability to read sports odds is one thing that novice sports bettors have a very hard time with. Point spreads and money lines are used to indicate one team being favored over another. Of the four major North American sports, point spreads are the dominant form of betting on football and basketball, while money lines are the preferred method for baseball and hockey because of the limited scoring in those two sports.

When betting with a point spread you are wagering that a particular team will win or lose by a certain amount of points. This pays out even-money minus the vigorish, or bookmakers take, which we will later explain further. To better understand how point spreads work let's look at a typical NFL oddsboard:

401 Buffalo Bills 49
402 New York Jets -4

403 Seattle Seahawks 39
404 San Francisco 49ers +3

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.

These are examples of 'side' betting with a point spread. There are also 'total' wagers that refer to the total amount of points scored by both teams. In the above example, the total, or "over/under," in the Bills-Jets game is 49. You can bet whether the final score will come in over or under that total by laying $110 to win $100.

Reading baseball and hockey lines can be a bit different. When using a money line you are betting which team will win outright, not by a specific amount of points. Secondly, the payouts differ on a money line as compared to the standard 11/10 odds of a point spread bet. The money line system requires more money to be risked on favorites and gives higher payouts to underdog players. To better understand how money lines work let's look at a typical Major League Baseball oddsboard:

103 San Diego Padres +135
104 Los Angeles Dodgers - 125

105 St. Louis Cardinals +190
106 Washington Nationals -220

The teams with the plus (+) are the underdogs and the number indicate how much you will win if you bet $100 on that particular team, while the minus (-) numbers show how much you need to risk in order to win $100. So a winning $100 bet on the Padres would pay $135. If you bet the Dodgers, you would have to risk $125 to win $100. The difference between the two numbers is called the 'dime line.' As seen in this example the dime line will increase based on how heavy a side is favored.

Vigorish

The vigorish, also known as 'the vig' or "juice," allows bookmakers to make money regardless of the outcome of a game or match. For example, the true odds when betting with a point spread is even-money, but in order to win $100 you have to bet $110. The $10 difference reflects the vig, or the bookmaker's commission.

The optimal situation for bookmakers is to set odds that will attract an equal amount of money on both sides, thus limiting their exposure to any one particular result. To further explain, consider two people make a bet on each side of a game without a bookmaker. Each risks $110, meaning there is $220 to be won. The winner of that bet will receive all $220. However, if he had made that $110 bet through a bookmaker he would have only won $100 because of the vig. In a perfect world if all bookmaker action was balanced, they would be guaranteed a nice profit because of the vig.

Rotation Numbers

In the sample odds boards listed above you may have noticed a set of numbers to the left of the team names. These are called 'rotation numbers' and are used by all bookmakers across North America. This helps expedite the wagering process and also makes comparing lines from various books much easier because the games are always displayed in the same order.