The lottery is the most popular form of gambling in the United States. People spend upwards of $100 billion on tickets every year, and the jackpots can be life-changing. But is it ethical for governments to promote such addictive and costly activities? And even if it is, does the public good really outweigh the harms of compulsive gambling and lower-income families?

A lottery is an arrangement in which a prize is offered for the chance to win it, based on consideration. To qualify, there must be a payment by the participant and a prize that can range from money to jewelry to a new car. Federal statutes prohibit the promotion of lottery games by mail or over the telephone, but these rules don’t necessarily affect what happens in state-run lotteries.

There’s a big difference between buying tickets and winning them. Many people try to increase their chances of winning by picking numbers that have a significance to them, like birthdays or ages, but this is not a wise strategy, Harvard statistics professor Mark Glickman says. Choosing numbers that are repeated or that are associated with significant dates reduces your odds of winning, because there is more than one person who will have those same numbers. Glickman recommends letting the lottery select your numbers or opting for Quick Picks instead of choosing your own.

Regardless of whether you play the lottery, it’s important to understand how they work and what your odds are. And if you’re lucky enough to be the winner of a major jackpot, be sure to set a spending plan to avoid getting sucked back into gambling.