A competition based on chance, in which numbered tickets are sold for a prize, usually money. Originally, the lottery was a lawful and sometimes charitable method of raising money; in modern times it is usually considered a form of gambling. Also called sortilegium, sortes, and casting of lots.

Lotteries have become an important source of revenue for public purposes, including education and infrastructure projects. However, they are also controversial because they promote gambling and can have adverse social consequences, particularly for poor people. Despite these concerns, governments continue to expand the scope of state-sponsored lotteries, and to promote them more vigorously through advertising.

The oldest known lotteries were probably conducted in the Low Countries during the 15th century to raise money for town fortifications and to help the poor. The lottery was a popular means of raising money in colonial America as well, and it played a major role in the funding of both private and public ventures, such as roads, canals, libraries, churches, and colleges. George Washington even sponsored a lottery to fund his expedition against Canada.

Today, most states run a lotteries, and they provide substantial revenue for a wide range of public programs. However, critics argue that the state should not be in the business of promoting gambling and should focus instead on other sources of income, such as sin taxes and income tax. Furthermore, the reliance on advertising to promote the lottery raises questions about whether it is appropriate for government to be in the business of encouraging people to spend money they may not have.