Lottery can mean any contest with a low probability of winning — from finding true love to getting hit by lightning. But it can also refer to state-run contests that promise big bucks for a very small group of winners. Even schools select students using a lottery system.

But despite their seeming randomness, lottery games are actually designed to keep players coming back for more. Everything from the ads to the design of lottery tickets to the math behind them is calculated to make sure players continue to play. It’s not that much different than how companies like video game manufacturers and tobacco makers use psychology to keep users hooked.

The first lottery-style events appear in the Roman Empire, where they were used as a kind of party game during Saturnalian revelries and offered prizes in the form of fine dinnerware to all ticket holders. They then spread to the Low Countries in the fifteenth century, where they helped raise money for town fortifications and the poor.

In the seventeenth and eighteenth centuries, states looked to lotteries for a painless way to tax their people without having to ask them to vote on a tax increase. Lotteries also played an unexpected role in the American Revolution, helping finance a variety of important government projects. And they became a major part of life in the new colonies, despite Protestant proscriptions against gambling.