A sports bet is a wager placed on the outcome of a sporting event. A sports bet can be placed on a single team or an entire tournament. A person who makes a sports bet is called a punter (popular in the UK) or a bettor (popular in the US). A company that accepts bets is known as a bookmaker, or a betting agency.

When placing a bet, the bettor should first decide what type of bet they want to place. The most common bet type is the moneyline. This bet pays out based on the odds that are available at the time of the bet, regardless of how much they fluctuate. The odds are set by the bookmaker using a system known as implied probability. This system assigns positive numbers to underdogs and negative numbers to favorites. The oddsmakers then combine these numbers to create a betting line.

In a sport like football, you can also place over/under bets. The sportsbook sets a number that it believes will comprise the total points, runs or goals scored in a game and the bettor must decide whether to bet over or under that number. This wager type requires more research than the other two, as a bettor must consider the offensive and defensive capabilities of the teams, injury news, weather reports and previous matchups.

A +EV bettor is much like a savvy supermarket shopper, seeking out items that will be cheaper to purchase than what the store prices them at. This will usually mean backing an underdog, although there are times when a more fancied selection is both a more likely winner and offers value, such as in the case of a tennis head-to-head match.