Definition
A betting line is the current price or handicap a sportsbook offers on a wager. It tells you what must happen for the bet to win and how much the payout is if it does. A line can be a point spread, moneyline, total, or prop price.
For American odds, positive odds show profit on a $100 stake: profit = stake × odds / 100. Negative odds show how much must be risked to win $100: profit = stake × 100 / |odds|.
Worked Example
If the line is Cowboys -3.5 at -110, Dallas must win by 4 or more points for the spread bet to cash. At -110, a $110 stake wins $100 in profit, for a $210 total return including the original stake.
If the same game moves to Cowboys -4.5 at -110, the price is the same but the handicap is worse for a Cowboys bettor because a 4-point Dallas win no longer covers.
Why It Matters
The betting line is the number a bettor must beat with their own projection. Comparing lines across sportsbooks helps find better prices, which can turn the same opinion into a stronger or weaker wager.