Glossary
Vig
The vig, also called the juice, is the margin a sportsbook builds into its odds. It is the reason the implied probabilities of all outcomes add up to more than 100 percent. The vig is how a book earns its money, and it is the tax every bettor quietly pays on each bet.
The vig is the sportsbook's built-in edge. When you see two evenly matched sides both priced at -110 instead of a fair +100, the extra amount you risk is the vig.
Here is the tell. Convert every outcome's odds into an implied probability and add them up. On a fair market they would total 100 percent. On a real market they total more, often around 104 to 106 percent on a standard two-way bet. That overage is the vig.
The vig is why winning half your bets is not break-even. You have to win often enough to overcome the margin baked into the price. Understanding it, and learning to strip it out of a line, is a core skill of a literate bettor.
The full explanation lives in the guide on how sportsbooks make money.
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