Lottery:
[countable] A competition based on chance in which numbered tickets are sold and the winners selected by random drawing. Prizes are usually cash or goods. A lottery is often organized by governments to raise money for public works or charities. It is also used as a synonym for gamble.
The first recorded lotteries were held in the fifteenth century in the Low Countries for the purpose of raising money to build town fortifications and to provide charity for the poor. They were popular and successful enough to spread throughout Europe, where they helped finance everything from the European settlement of America to the founding of Harvard, Yale, and Princeton. The British Crown even chartered a national lottery to provide funds for public buildings and highways.
Lotteries need a mechanism to pool money from ticket purchases as stakes. This is usually accomplished by a system of ticket sales agents who pass the money paid for tickets up through a hierarchy until it reaches lottery headquarters to be pooled and drawn at random. In some cases computers are used to record and draw the winning numbers.
A key consideration in a lottery is balancing the odds against winning with the desire for large jackpots. If the odds are too easy, people will not play; if the odds are too high, ticket sales will decline. Historically, the odds of winning have been adjusted by increasing or decreasing the number of balls in the game to increase or decrease the chances of a win.