Odds Are Prices
Odds do two jobs at once: they describe the payout attached to an outcome and imply a probability. Different formats can display the same underlying price. American odds use positive and negative numbers, decimal odds show the total return per unit staked, and fractional odds show profit relative to stake.
American Odds
Negative American odds show how much must be risked to win 100 units of profit. At -110, a 110-unit risk returns 100 units of profit if successful. Positive odds show the profit on a 100-unit stake: +150 means 150 units of profit on 100 staked.
Decimal Odds
Decimal odds include the returned stake. A price of 1.91 means a successful 1-unit stake returns 1.91 total: the original 1 unit plus 0.91 profit. Decimal format is convenient for comparing markets and calculating implied probability.
Why Prices Move
Odds change when new information arrives or the market changes: injuries, lineups, starting pitchers, weather, role changes and betting activity can all move a number. Sports4Play records the original price when a pick is published instead of rewriting it later.