With the exception of casual bets between friends over sports matches, sports betting is usually carried out with the help of a bookie. Legal bookmakers exist all around the world and, in areas where sports betting is illegal, players commonly make their sports bets on the Internet with an online bookmaker. There are many price-per-head bookmaking websites that will take wagers on all sporting events in the world.

The general role of the bookmaker is to act as a market maker for sports bets, most of which have only two possible outcomes: a team either wins or loses. The bookmaker takes wagers for both possible outcomes and maintains a point spread, which will ensure a profit for the bookie regardless of the outcome of the wager. Bookmakers handle different types of bets all of which ensure they get their profit while paying out the winner of the wager. The following are just some of the most common bet types used by bookmakers.

Preposition bet: A preposition bet is when a player bets on a very specific outcome of a match instead of just a win condition. For example, placing a wager on the number of goals a soccer team will score on a given match, betting on a specific player scoring a goal, or wagering on the total yardage a wide receiver in a football game will net.

Parlay: A group of wagers that can go up to the dozen and that have a larger payout for the bettor than if he had made the individual bets, provided that the bettor wins all bets in the parley. A variant often called “progressive parlay” exists in which some of the bets can lose and a reduced payout is made.

Teaser: In a teaser, the bettor combines his bets on multiple games, adjusting the point spreads for each game but having a lower payout in the event of a win.

Run line: Also called goal lines in soccer, run lines are variant wagers with a fixed spread that usually offers a higher payout to the bettor in case the favorite team wins and a lower payout in case the home dog wins.

Future bet: We call “future bets” wagers made in the long-term, for games that will usually happen several months in the future—for example, betting that your favorite team will win the Superbowl before the start of the season. There are usually very high payout rates associated with future bets since the risk factor is very high.

Head-to-head bet: These wagers involve bettors predicting the results between two of the players in a team (scores, goals, points, yards, and such) regardless of the overall result of the match.

Flexible-rate bet: Also known as “totalizators”, flexible-rate wagers feature dynamic odds that change according to the share allocated to each possible outcome, taking into account the return rate of the bookmaker that offers the bet.