Tournaments and Officials

Entry-level professional tournaments are called satellite events and are arranged in four-tournament "segments." A player must compete in all four events on a satellite segment to earn ranking points. These tournaments offer unranked and lower-ranked players the opportunity to compete for the ranking points that enable them to qualify for challenger series tournaments, which offer more prize money. At the challenger level, players also compete for ranking points that are determined by their performance in each individual event. Successful players at this level can then compete at the tournaments sponsored by the professional tours.
	Annual tennis tournaments operated by the professional tours, such as the Japan and Italian opens, are held throughout the world between the months of January and November. They involve varying amounts of prize money, and some tournaments are considered more prestigious than others and thus attract better players. Matches in tournaments are arranged by a system called seeding. By seeding players in certain places within the pool of players, or draw, according to their abilities and past performances, organizers ensure that the best players do not compete against each other until the later rounds of a tournament. Unanticipated upsets, in which unseeded or lower-seeded players defeat higher-seeded players in early rounds, often add excitement to tournaments. Tournaments involve up to 128 players and seven rounds of play. The ATP Tour operates about 85 tournaments each year, while the WTA Tour operates about 60 competitions annually.
While most recreational matches are refereed by the players themselves, in most tournament competitions officials keep score, determine if shots are good, and interpret rules. The head official on the court, called the chair umpire, sits on a tall chair at one end of the net. A varying number of line judges sit around the court beyond the path of the players. Line judges determine whether serves and shots are good or out. A net-cord judge may be employed to determine when a ball touches the top of the net, and a foot-fault judge may watch for that specific infraction. In the 1980s electronic devices began to be used in professional tournaments to determine if serves, whose speeds may reach over 100 mph (161 km/h), land in or out of the service box.