The US Open is in full swing, in case your tennis-loving friends haven’t told you yet. While the wildly popular game has been around since the twelfth century, when players used their bare hands to swat the ball back and forth, you are not alone if you haven’t given in to the hype.

Keep reading for a quick reference guide (or refresher) on tennis terms to know while watching the US Open Tennis Championships.

Love means nothing.

Seriously. Love is a score-keeping term in tennis that means zero. So a score of 15-love is 15-0.

It takes two to deuce.

This means the score of the match is tied at 40-40, and one player will need to score twice in a row to take the win. And the Honey Deuce is the official cocktail of the US Open. For those more interested in the latter, check out this recipe.

Take advantage.

Building off of deuce, when a player scores following deuce, they have the advantage. If they score a second time in a row, they win. If not, the match continues. And this can go on for a while. During Wimbledon in 2010, John Isner and Nicolas Mahut took the title for the longest tennis match ever played, after their match lasted a total of 11 hours and 5 minutes.

Going for a grand slam

Every year, there are four major tennis tournaments: the Australian Open, the French Open, Wimbledon and the US Open. If a player wins all four in a calendar year, they earn a Grand Slam title. Players can also get a Career Grand Slam title by winning all four throughout their entire career.