A lottery is a game with three elements for players: a prize to win, a chance to win, and an element of consideration to participate. It is a form of gambling, but it also has a sense of civic duty and meritocracy that is unique among many other forms of gambling.
The basic elements of a lottery are quite simple: a mechanism for recording the identities and amounts staked by each participant; a means for collecting and pooling all money staked as stakes; and a system for selecting winners. Typically, a bettor will write his name on a ticket that is deposited with the lottery organization to be shrunk and possibly selected for a drawing. Afterward, a percentage is usually deducted for the costs of organizing and promoting the lottery, and the remainder goes to the winners.
Most people would rationally reject an arrangement in which they hand over a dollar and receive only fifty cents back. Yet, a significant proportion of the population willingly accepts lotteries with expected values lower than their cost of participation.
The reason for this is that lottery participants believe that they are helping to benefit the state, or at least are doing a good deed. This belief is likely a legacy of the post-World War II period, when states were expanding their social safety nets and wanted to avoid especially onerous taxes on the middle class and working class. That arrangement eventually broke down, and lotteries were introduced as a way of raising funds without taxing those in need.