Definition of Opening Line

What does the term "opening line" mean in the world of sports betting? What is the definition of the term "opening line"?

The "opening line" is the first line that is made available for betting on a sporting event. The bookmakers need to set an initial line on an event and this is known as the "opening line".

So, let's say that the Denver Broncos and Seattle Seahawks win their conference championships and are now set to do battle in the Super Bowl. The "opening line" would be the first available betting line for the game. So, for instance, let's say that the opening line looks something like this:

Seattle, +3
Denver, -3

So, the opening line would have the Denver Broncos as three point favorites.

Once people start putting money down on the game, the line is probably going to change. For instance, let's say that the money of the casual betting fan comes in on the Denver Broncos. In that case, the opening line would change, and the new line might look something like this:

Seattle, +4.5
Denver, -4.5

The goal of the sports book is to have equal amounts of money come in on both sides, so that their exposure to one side isn't bigger than the other. So, if the majority of the money is coming in on the Broncos, the sports books will constantly adjust the lines to keep their exposure the same.

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Note: knowledgeable sports fans can take advantage of the early lines to get their money down on favorable situations. For instance, in the UFC, the opening lines will constantly be considerably different than the final lines before the fight begins. The lines for UFC fights will often fluctuate considerably before settling down after a couple of days.