The US Open Tennis Championships is a hardcourt tennis tournament held annually in Queens, New York. Since 1987, the US Open has been chronologically the fourth and final Grand Slam tournament of the year. The other three, in chronological order, are the Australian Open, French Open and Wimbledon. The US Open starts on the last Monday of August and continues for two weeks, with the middle weekend coinciding with the US Labor Day holiday. The tournament is of one of the oldest tennis championships in the world, originally known as the U.S. National Championship, for which men's singles and men's doubles were first played in August 1881. It is the only Grand Slam that was not affected by cancellation of World War I and World War II or interrupted by the COVID-19 pandemic in 2020.

The tournament consists of five primary championships: men's and women's singles, men's and women's doubles, and mixed doubles. The tournament also includes events for senior, junior, and wheelchair players. Since 1978, the tournament has been played on acrylic hardcourts at the USTA Billie Jean King National Tennis Center in Flushing Meadows–Corona Park, Queens, New York City. The US Open is owned and organized by the United States Tennis Association (USTA), a non-profit organization, and the chairperson of the US Open is Patrick Galbraith. Revenue from ticket sales, sponsorships, and television contracts is used to develop tennis in the United States.

This tournament, from 1971 to 2021, employed standard tiebreakers (first to 7, win by 2) in every set of a singles match.^[2] Since 2022, when a match that reaches 6–all in the last possible set (the third for women and the fifth for men) an extended tiebreaker to 10 points is played. Should the tiebreaker be tied at 9-all, whoever scores two straight points wins it.