The Presidents Cup happens every two years (it's a biennial event currently on odd-numbered years), pitting 12-man teams representing the United States and the International team (everywhere but the U.S. and Europe) against each other in 30 matches over four days to determine a winner.
How Presidents Cup teams are picked
Each team is headed by an appointed captain, with the PGA Tour choosing both the American captain (in 2019, Tiger Woods) and the International captain (in 2019, Ernie Els). The host team alternates each match, as well, with the matches played in odd-numbered years. The U.S. hosts in 2021, 2025, 2029, etc. The International team hosts in 2019, 2023, 2027, etc.
The two teams are determined by qualifying systems created by the captains and co-owning organizations.
The American team is currently crafted from 8 automatic qualifiers, who earn a spot on the team based on a points system that spans approximately 20 months from March of the off-year in the cycle to the end of the cycle. After those players are determined, the American captain then hand picks a total of four wild-card players to round out the team.
The European team is also currently decided first from 8 automatic qualifiers, all based on currently standing in the Official World Golf Ranking at the end of the qualifying cycle. The 8 highest-ranked eligible players make the team. Then the captain can pick four wild-card players to round out the team.
Presidents Cup format, matches, points and rules
During the week of the Presidents Cup, the matches are scheduled from Thursday through Sunday, with 30 matches altogether. If either team earns at least 15.5 points, they win the Presidents Cup. There is no tie for a 15-15 finish. There will be a winner.
On each of the first two days, a total of 10 matches are played over two, five-match sessions each day featuring two different types of two-man match-play matches each day. In one of those days, there will be one five-match session of what's called foursomes. On the other, there's a session of what's called fourball.
On Saturday, the third day, there will be eight matches played over a two, four-match sessions. There will be one session of fourballs or foursomes in the morning, with the opposite format in the second afternoon session.
Foursomes is also called alternate shot. On each hole, one player (Player A) from each team hits their team's respective tee shots. Then the other player (Player B) from each team hits the second shot. Then the third shot is hit by Player A, and so on, until the ball is holed. The teams compare scores, and the team with the lower score wins the hole. Whichever team wins the most holes wins a full point. If the match is even after 18 holes, then the match is halved and each team earns 0.5 points.
Fourball is also called best ball. On each hole, all four players play out the hole using their own ball, just like they were playing individually. At the end of each hole, each team uses the better score of the two partners and compares it to the other team. The team with the better score wins the hole. Whichever team wins the most holes wins a full point. If the match is even after 18 holes, then the match is halved and each team earns 0.5 points.
All of the teams are announced before the session starts, slotted by match position. In the team sessions each player on each team must be used once in the first four sessions. (In 2017, each player had to be used at least twice in the first four sessions.)
On the final day, a total of 12 matches are played in one session. All 12 players from each side are announced by the captains in a ceremony before Sunday play, slotted by match position. It's classic match play, with the player winning the most holes winning the match and a full point. If the match is even after 18 holes, then the match is halved and each team earns 0.5 points.