Lottery is a form of gambling in which numbers are drawn to determine prizes. Typical prizes are money or goods. Lotteries are run by state or private organizations. They may be government-controlled, involving the state or a private firm assuming responsibility for organizing and running the lottery in return for a profit share. The first recorded public lotteries to award prizes in the form of money appeared in the Low Countries during the 15th century, when towns sought funds for town fortifications and to aid the poor. The name lottery is probably derived from the Dutch word lot (fate) or the French word loterie (a play on words referring to the action of drawing lots).

Buying a ticket in the hope of winning is a risk-taking behavior that cannot be explained by decision models based on expected value maximization. However, other models incorporating risk-seeking behavior and utilities defined on things other than the lottery outcomes can account for ticket purchases. Lottery plays are often motivated by the desire to experience a thrill and indulge in fantasies of wealth.

The odds of winning a lottery are independent of the number of tickets purchased. The odds of winning remain the same if you buy one ticket or ten, and your chances of winning are no higher after playing for a long time. In fact, the odds of winning the lottery decline as the number of tickets sold increases, indicating that people are becoming bored with the game.