The vig — short for vigorish, also called juice — is the sportsbook's built-in commission on every bet.
On a -110 bet, you pay $110 to win $100. If the book takes $110 from each side, they collect $220 and pay out $210 — keeping $10 regardless of who wins.
Because of the vig, you need to win 52.4% of your bets to break even at -110. That's the house edge baked into every single bet.
Shop lines across books. If DraftKings has -110 and FanDuel has -105 for the same bet, always take -105. The difference compounds significantly over hundreds of bets.
The vig is unavoidable but you can minimize it. Always shop for the best line. This is why sharp bettors have accounts at 4-5 sportsbooks.