One of the first enterprises to take advantage of the plethora of information and consumers on the internet was sportsbooks. Online sportsbooks typically use various computations and algorithms to come up with their lines. The difference between this line and the lines set in Las Vegas casino sportsbooks is known as the off line.
Professional gamblers who bet on sports will often seek out exactly the line they want for a given contest. In order to do so, they must gather betting lines from online sportsbooks and Las Vegas casinos (Las Vegas is the center of sports betting in the US). These professionals use the off lines to determine how far off the sportsbooks in Vegas are from the lines they want. They can use this figure to determine the value of buying points in a point spread or where they want to place a wager. Casual players may use the off lines to compare the experts in Las Vegas to the computer algorithms used by their favorite online sportsbook. In practice, the off lines are useful for evaluating lines, but hold no bearing on the amount won or lost on a given wager.