To bet means to risk something valuable, usually money, on the outcome of an event you're not sure about. When people bet on a football game, they might say “I bet the home team wins,” and put money on that prediction. If they're right, they win money. If they're wrong, they lose what they risked.

Kids make informal bets all the time: “I bet I can run faster than you” or “I bet it's going to rain tomorrow.” These aren't usually about money, just friendly predictions or challenges. When you say “I bet” in conversation, you're expressing confidence that something is true.

A bet can also be the thing you're risking: “He made a bet with his sister that he could finish his homework in under an hour.”

The phrase you bet is a cheerful way to say “yes, definitely!” If someone asks “Can you help me with this?” you might answer “You bet!” meaning you're happy to help.

Betting for money is gambling, which is heavily regulated because people can lose more than they can afford. Most forms of betting are illegal for children.