Sports betting glossary

Alternate Line

An alternate line is a non-standard spread, total, or player prop line offered alongside the main line, with adjusted odds. Buying a more favorable line costs juice; selling a less favorable line earns juice.

Arbitrage

Arbitrage is placing bets on every possible outcome of an event across different sportsbooks at prices that guarantee profit regardless of result. It exploits pricing disagreements between books rather than predicting outcomes.

Bankroll Management

Bankroll management is the practice of sizing each bet as a fixed percentage of total bankroll, capping risk per wager, and protecting against ruin during inevitable losing streaks. It is the single most important habit separating long-term winners from losers.

Closing Line Value

Closing line value is the difference between the odds at which a bet was placed and the final closing odds. Beating the closing line consistently is the strongest single indicator that a bettor is making profitable decisions.

Confidence Interval

A confidence interval is a range that quantifies the uncertainty around a point estimate. A 95% confidence interval is the range within which the true value would fall in 95 out of 100 repeated samples, given the modeling assumptions.

DFS

DFS is a contest format where users assemble lineups of real athletes under a salary cap and compete based on those athletes' real-game statistical performance. DraftKings and FanDuel are the dominant DFS operators in the US.

Dutching

Dutching is splitting a stake across multiple outcomes of the same event in proportions that return an equal payoff regardless of which selection wins. It is used when a bettor believes the true probability of any of several outcomes exceeds the combined implied probability.

Expected Value

Expected value is the average profit or loss a bet would return if placed an infinite number of times at the same odds and probability. Positive EV means the bet is mathematically profitable long term; negative EV means it loses money.

Fading the Public

Fading the public means betting against the side that most recreational bettors are backing. The strategy is built on the observation that books shade lines toward popular sides, leaving value on the contrarian side.

Flat Betting

Flat betting is the practice of staking the same amount on every wager, regardless of confidence or recent results. It maximizes resistance to tilt and minimizes variance compared to confidence-weighted staking schemes.

Futures

A futures bet is a wager on a long-term outcome resolved at the end of a season or tournament, such as a league champion, division winner, or season MVP. Futures markets carry high vig but offer large potential payouts.

Hedge

A hedge is a second bet placed on the opposite side of an existing wager to lock in profit or reduce loss regardless of outcome. Hedging is a risk-management tool, not an edge-generating strategy.

Hold Percentage

Hold percentage is the share of total wagers a sportsbook expects to keep as profit across a market, computed from the vig built into the odds. It is the book-side equivalent of vig from the bettor's perspective.

Implied Probability

Implied probability is the win probability a set of betting odds implies, derived by converting the odds into a percentage. It represents the rate at which a bet must win to break even at that price.

Juice

Juice is the bettor-side term for the commission a sportsbook charges, baked into the odds rather than billed separately. Standard juice on a two-way market is -110, meaning a bettor risks $110 to win $100 on either side.

Kelly Criterion

The Kelly criterion is a stake-sizing formula that computes the optimal fraction of bankroll to bet given an edge and odds, maximizing long-run logarithmic growth. Full Kelly maximizes growth but produces high variance; fractional Kelly (typically half or quarter) is more practical.

Line Shopping

Line shopping is the practice of checking the same bet across multiple sportsbooks and placing the wager at the book offering the most favorable odds. It is the single highest-ROI habit any bettor can adopt.

Log5

Log5 is a formula that combines two independent rate statistics (typically batter vs. pitcher) into a single matchup-adjusted probability, accounting for the league average. It is the workhorse equation for head-to-head probability modeling in baseball.

Moneyline

The moneyline is a bet on which team or competitor will win a game outright, without point-spread adjustment. Odds are expressed as American odds, with negative numbers indicating favorites and positive numbers indicating underdogs.

Over/Under

Over/under refers to a bet on whether a statistic (a game total, a player prop, a team total) will finish above or below a posted line. It is the most general two-way market structure in sports betting.

Pace

Pace is the number of offensive possessions a team averages per game, expressed per 48 minutes in the NBA. Faster pace means more total possessions, more total shots, and inflated counting stats for every player on the floor.

Parlay

A parlay is a single bet that combines two or more individual wagers (legs). Every leg must win for the parlay to pay out; one losing leg voids the entire bet. Payouts multiply across legs, producing large potential returns and large built-in house margins.

Parlay Builder

A parlay builder is a sportsbook tool for combining legs from a single game into one parlay ticket, priced with correlation adjustments. Same-game parlays are among the highest-vig products sportsbooks offer.

Player Prop

A player prop is a bet on an individual athlete's statistical performance in a game, independent of game outcome. Common props include points, rebounds, assists, passing yards, receiving yards, strikeouts, and home runs.

Point Spread

A point spread is a market that handicaps the favorite by a number of points, requiring the favorite to win by more than the spread for a bet on the favorite to cash. The underdog covers by either winning outright or losing by less than the spread.

Prop Builder

A prop builder is a sportsbook feature that lets bettors combine multiple player or game props from the same game into a single ticket with a custom price. Most prop builders are correlated parlays under the hood and carry high vig.

Pythagorean Expectation

Pythagorean expectation estimates a team's true win percentage from points scored and points allowed, using an exponent calibrated per sport. It often diverges from actual win-loss record and is a stronger predictor of future performance.

Regression to the Mean

Regression to the mean is the statistical tendency for extreme observations to be followed by less extreme ones, moving closer to the long-run average. Hot streaks cool and cold streaks warm, in any process driven partly by chance.

Sample Size

Sample size is the number of observations used to compute a statistic. Small samples produce noisy, unreliable estimates; large samples converge on the true underlying rate. Every statistical claim in betting must be evaluated against the sample size that produced it.

Sharp Money

Sharp money is action from professional bettors with proven long-term edges. Books treat sharp action as the most informative signal in the market, often moving lines on sharp bets even before public volume catches up.

Sportsbook

A sportsbook is a licensed operator that accepts wagers on sporting events, setting odds and managing risk across bets. Major US sportsbooks include DraftKings, FanDuel, BetMGM, Caesars, and ESPN Bet.

Steam Move

A steam move is a sudden, synchronized line movement across multiple sportsbooks within a short window, triggered by heavy sharp action or new information. It signals that smart money has moved the market.

Team Prop

A team prop is a bet on a single team's statistical performance in a game, independent of the opponent's score or the game outcome. Common team props include team totals, first-half scoring, and team-specific milestones.

Total

A total (also called over/under) is a market that prices the combined final score of both teams in a game. Bettors wager on whether the actual total will finish over or under the posted number.

True Shooting Percentage

True shooting percentage is a basketball efficiency metric that measures a player's scoring rate per shot attempt, weighting two-pointers, three-pointers, and free throws by their relative value. League-average TS% in the NBA hovers around 57%.

Usage Rate

Usage rate is the percentage of a team's offensive possessions that end with a given player's shot attempt, free throw trip, or turnover while that player is on the floor. It quantifies how central a player is to the team's offense.

Vig

Vig is the sportsbook's built-in commission on a bet, expressed as the percentage by which the combined implied probabilities of all outcomes exceed 100%. It is how books guarantee profit independent of bet outcomes.