FIDE's most visible activity is organizing the World Chess Championship since 1948. FIDE also organizes world championships for women, juniors, seniors, and the disabled. Another flagship event is the Chess Olympiad, a biennial chess tournament organized since 1924, in which national teams compete. In alternate years, FIDE also organizes the World Team Championship, in which the best teams from the previous Olympiad compete.As part of the World Chess Championship cycle, FIDE also organizes the Candidates Tournament, which determines who will challenge the reigning World Champion, and the qualifying tournaments for the Candidates, such as the Chess World Cup, the FIDE Grand Prix, and the FIDE Grand Swiss Tournament 2019.FIDE is recognized by the International Olympic Committee (IOC) as the supreme body responsible for the organization of chess and its championships at global and continental levels. Other tournaments are not overseen directly by FIDE, but they generally observe FIDE rules and regulations. Some national chess organizations such as the US Chess Federationuse minor differences to FIDE rules.FIDE defines the rules of chess, both for individual games (i.e. the board and moves) and for the conduct of international competitions. The international competition rules are the basis for local competitions, although local bodies are allowed to modify these rules to a certain extent. FIDE awards a number of organizational titles, including International Arbiter, which signifies that the recipient is competent and trusted to oversee top-class competitions. FIDE calculates the Elo ratings of players. Main article: FIDE titlesFIDE awards titles for achievement in competitive play, such as the Grandmaster title. It also awards titles to composers and solvers of chess problems and studies.Correspondence chess (chess played by post, email or on online servers) is regulated by the International Correspondence Chess Federation, an independent body that cooperates with FIDE where appropriate.The FIDE budget for 2019 is 5.5 million euros. This income comes mostly from tournament registration, entry fees, and rights for the Olympiad and World Championship, but during the last year the amount received from corporate sponsorship has sharply increased from 5% to 15%, and the new FIDE President Arkady Dvorkovich is aiming at reaching the 50% benchmark in the near future.