What is a Grand Slam in tennis and golf?

In both sports, a Grand Slam is the set of four most important annual tournaments — and, in its strictest sense, winning all four in the same calendar year.

Tennis has the Australian Open in January, the French Open at Roland Garros in May, Wimbledon in June and July, and the US Open in August and September. They are distinguished from other events by prize money, ranking points, and being best-of-five sets in men's singles.

The surfaces differ, which is why winning all four is so hard: hard court in Australia, clay in Paris, grass at Wimbledon, hard court in New York. Each rewards different movement and tactics.

Golf's four majors are the Masters in April, the PGA Championship in May, the US Open in June and The Open Championship in July. The men's calendar Grand Slam has never been achieved.

The terminology causes confusion because it is used three ways. Commentators call each individual tournament "a Grand Slam", so a player can be described as having won 20 of them. Winning all four in a calendar year is the original strict meaning. Winning all four at some point in a career, not necessarily consecutively, is a career Grand Slam — a considerable but much more common achievement.

Holding all four simultaneously across two calendar years is sometimes called a non-calendar-year Grand Slam, and in golf the equivalent was widely nicknamed after the player who did it.

The phrase itself is borrowed from contract bridge, where a grand slam means winning all thirteen tricks.

Women's golf recognises five majors rather than four, which the men's calendar does not, so the arithmetic of a Grand Slam differs between the two tours. Tennis is the same four events for both.