Official lottery is a form of gambling in which the prize is based on the drawing or casting of lots. The practice has a long history, including several instances in the Bible, but it became especially popular during the fourteenth century in the Low Countries, where it was used to finance town fortifications. Today, it is common worldwide and is an important source of income for state governments.
Although lotteries have a wide appeal, they are not without controversy. Some critics claim that they promote addictive gambling behavior and impose a significant regressive tax on poorer groups. Others argue that the state faces a conflict between its desire to increase revenue and its duty to protect the public welfare.
The prizes can be a fixed amount of cash or goods, or they can be a percentage of the total receipts. The latter format, which is the most common, requires the organizer to assume a risk that the total receipts will not be sufficient to cover the prize fund.
In the latter case, if the prize pool is not enough to cover all the ticket sales, the prizes will not be awarded. However, the prize funds can be replenished as necessary. In addition, some modern lotteries allow the purchaser to choose his or her own numbers from an acceptable pool. This allows for the possibility of multiple winners and increases the chances of winning. In any event, the enabling statutes, official rules, regulations and procedures of each jurisdiction govern all aspects of the lottery, including the award of prizes.