Odds describe the likelihood of something happening, or how probable an event is compared to it not happening. When someone says “the odds are against you,” they mean success is unlikely. When they say “the odds are in your favor,” they mean you have a good chance of succeeding.

In gambling and statistics, odds express probability as a ratio. If the odds of rain tomorrow are 3 to 1, rain is three times more likely than no rain. If the odds of winning a raffle are 1 in 100, you have one chance out of a hundred tickets. People who run betting games use odds to determine how much money gamblers can win: lower odds mean something is more likely to happen, so the payout is smaller.

The word appears in several common phrases. When you overcome the odds, you succeed despite low chances of success. When something happens against all odds, it occurs even though it seemed nearly impossible. If you're at odds with someone, you disagree or are in conflict with them.

Understanding odds helps you think clearly about risk and probability. For example, if the odds of getting struck by lightning are very low, it usually isn't worth worrying about. If the odds of passing a test without studying are quite low, you know where to focus your effort.