who were members of French clubs. Thus, Wimbledon, the US Open, the French Open and the Australian Open (dating to 1905) became and have remained the most prestigious events in tennis. Together, these four events are called the Majors or Slams (a term borrowed from bridge rather than baseball). In 1913, the International Lawn Tennis Federation (ILTF), now the International Tennis Federation (ITF), was founded and established three official tournaments as the major championships of the day. The World Grass Court Championships were awarded to Great Britain. The World Hard Court Championships were awarded to France; the term "hard court" was used for clay courts at the time. Some tournaments were held in Belgium instead. And the World Covered Court Championships for indoor courts were awarded annually; Sweden, France, Great Britain, Denmark, Switzerland and Spain each hosted the tournament. At a meeting held on 16 March 1923 in Paris, the title "World Championship" was dropped and a new category of "Official Championship" was created for events in Great Britain, France, the US and Australia – today's Grand Slam events. The impact on the four recipient nations to replace the "world championships" with "official championships" was simple in a general sense: each became a major nation of the federation with enhanced voting power, and each now operated a major event. The comprehensive rules promulgated in 1924 by the ILTF have remained largely stable in the ensuing 80 years, the one major change being the addition of the tiebreak system designed by Jimmy Van Alen. That same year, tennis withdrew from the Olympics after the 1924 Games, but returned 60 years later as a 21-and-under demonstration event in 1984. This reinstatement was credited by the efforts of then ITF president Philippe Chatrier, ITF general secretary David Gray and ITF vice president Pablo Llorens, with support from International Olympic Committee president Juan Antonio Samaranch. The success of the event was overwhelming, and the IOC decided to reintroduce tennis as a full-medal sport at Seoul in 1988. The Davis Cup, an annual competition between men's national teams, dates to 1900. The analogous competition for women's national teams, the Fed Cup, was founded as the Federation Cup in 1963 to celebrate the 50th anniversary of the founding of the ITF. In 1926, promoter C. C. Pyle established the first professional tennis tour with a group of American and French tennis players playing exhibition matches to