Lottery is a form of gambling whereby participants pay for the chance to win a prize based on random selection. The casting of lots for decisions and fates has a long history, but the lottery as a mechanism for material gain is more recent. State-sanctioned lotteries have become popular, and are a major source of state revenue in many countries. They are widely criticized, however, for their alleged promotion of addictive gambling behavior and their regressive impact on lower-income groups.
A key element in all lotteries is a pool of stakes paid for by participants, usually a percentage of total ticket sales (often deducted for costs of organizing and promoting the lottery). From this pool, the winning numbers or symbols are drawn at random to determine the winners. The winning tickets are extracted from the pool after being thoroughly mixed, typically by mechanical means such as shaking or tossing; this ensures that chance, not skill, determines the results of each drawing. Whether the pool is large or small, a proportion is usually set aside for the organizers as revenues and profits, and a larger percentage is awarded to the winner or winners. Lottery organizers face a difficult decision: to promote and advertise a few large prizes or to offer more frequent chances to win smaller sums of money, in the hope that people will be attracted by the prospect of winning a much larger prize. Those who do not win often feel that they must continue to play in order to have a chance of winning.