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ATLANTIC CITY, N.J. (AP) — Sports betting is now legal in Ohio, as well as two-thirds of the country, and more Americans than ever before have an opportunity to place a legal bet on Sunday’s Super Bowl.

With sports betting ads blitzing the airwaves with come-ons and promotions, things might be a bit confusing, especially for first-time bettors or those who don’t fully understand how things work.

Here is a guide to betting on the big game between the Philadelphia Eagles and the Kansas City Chiefs. We will deal here only with legal options from sportsbooks approved and regulated by government authorities in the U.S.

What is a point spread? Over/under what?

Two of the most popular bets are on the point spread (the number of points by which a team must win the game in order for the bet to be a winner) and the total, also known as the over/under (the total number of points scored by both teams).

Contrary to popular belief, the point spread is not a consensus on how many points oddsmakers think one team will win by. Rather, it is a number designed to generate as close to an equal number of bets on both sides as possible. That way, the oddsmakers are guaranteed a profit through a cut of the action, called the vigorish, or “vig.” (Many books, hoping to sound less wiseguy-ish, call it “the price.”) Most sportsbooks will keep 10% or more of a winning bet before paying you the rest, but they keep 100% of all losing bets. Prices on Super Bowl bets can vary significantly, so it pays to shop around to get the lowest price you can before making a bet.

Beating the spread is known as “covering.” For the Eagles to cover their spread of 1.5 points, they must win the game by 2 or more points. Conversely, underdog Kansas City can cover by either winning the game outright, or losing by less than 2 points. (Odds and point totals are as of Friday from FanDuel, the official odds provider for The Associated Press.) The spread can change up until kickoff — and even afterward, during live betting, we’ll get to that later — but the number locks in once you make a bet.

A spread with a whole number, say, 2 points, opens the opportunity for what’s called a “push” if the winning margin ties. You don’t win anything but you get your original bet refunded. This also applies to other bets, which is why most of them involve a fraction, like 44.5 yards or 48.5 points.

Don’t want to bother with points and just pick the winner? That’s called the money line. A bet on the Eagles to just win the game, regardless of the score, is somewhat less profitable than using a point spread. You will have to bet $122 of your own money to win $100. (Of course you get your original $122 back as part of the $222 payout.) A money line bet on Kansas City, however, will win $104 on a $100 bet, for a total payout of $204.

If you believe the game will be a high-scoring affair, you might want to make a bet on the total, currently 50.5 points. That means if you bet the over, both teams combined must score at least 51 points for your bet to win. If it doesn’t, people who bet the under will win.

Can I make my own odds?

Yes. But that can be costly. You can pick your own spread or total — an alternate — to improve your chance of winning, but the farther your pick deviates from the sportsbook’s number, the less it will pay if you win. (You also can choose a harder-to-reach number for a higher potential payout, such as betting that the Chiefs will win by 20 points, but that’s a very risky strategy.) So if all you want to do is bet Kansas City with the point spread, but you want to get more points than the 1.5 currently being offered, you can bet on an alternate spread, such as Kansas City getting 3.5 points. That’s helpful if you think the game might be decided by a 3-point field goal, and you want an extra cushion. But because you’re grabbing better odds for yourself, the bet is a more costly one: You must put up $166 of your own money to win $100 in that case. Additional bets can be tacked on as part of so-called same-game parlays, which are combinations of bets on the same game. But the more combined outcomes you bet on, the greater the likelihood that at least one of them will lose, sending your entire parlay down in flames.

What else can I bet on?

If this sounds like a lot to take in, there are much simpler ways to bet on the game, including some aimed at the casual fan or even someone who knows nothing at all about football. A perennial favorite is betting on the coin flip at the start of the game to determine which team can choose to get the ball first. There are only two choices: heads or tails. You can even bet on which color of Gatorade the winning coach will be doused in at the game’s conclusion. Seriously.

This is what’s called a proposition or “prop” bet. It involves betting on whether a particular event will or won’t happen during the game, and there is a vast array to choose from. They can be disarmingly simple, such as guessing which team will get the ball first, whether the first score of the game will be a touchdown or a field goal, and whether or not the game will go into overtime.

Prop bets based on a particular player’s performance are always popular during the Super Bowl. You can bet on whether Chiefs quarterback Patrick Mahomes will pass for over or under 294.5 yards, how many catches his favorite target, tight end Travis Kelce, will have (over or under 7.5) or how many touchdown passes Eagles quarterback Jalen Hurts will throw.

Can I bet while the game is being played?

People with online sportsbook accounts can bet on ever-changing outcome odds as the game is being played; live-betting is the fastest-growing segment of sports betting. For instance, the game starts with the Eagles favored by 1.5 points, but say Kansas City scores two quick touchdowns to take a 14-0 lead. The in-game odds will change to reflect the current situation, and you can now bet on whether Kansas City will win by 14 points, or whether the Eagles will lose by less than that. Or say the Chiefs’ top receiving weapon Kelce is being shut down by Eagles defenders, and appears unlikely to eclipse his pregame receiving yards total of 79.5 yards. Bettors can wager on whether he will or won’t eclipse a lower number.

A word of caution, though: The number of these in-game bets and the rapidity with which odds change can be dangerous for those with a gambling problem, and many experts fear they could even tip a casual gambler toward becoming one with a problem. Some good advice: Set a budget in advance of money you can afford to lose, and stick to it. Look at betting on the game as a form of entertainment and not as a way to gain money that you need. If things head south, don’t make additional bets to try to win back what you’ve lost. This is one of the quickest ways gamblers dig themselves a deep hole.

What if I think I might have a gambling problem?

Betting on the Super Bowl is supposed to be fun, and for most people, it is. But for others, compulsive gambling is a serious problem. For help, call 800-GAMBLER.