Tennis players are athletes who compete in the sport of tennis, which involves hitting a ball over a net using a racket. They can play singles, where one player faces another, or doubles, where two players team up against another pair. Players must have good hand-eye coordination, agility, and stamina to succeed in matches. Professional tennis players often compete in tournaments, such as the Grand Slam events, which include the Australian Open, French Open, Wimbledon, and US Open. They train rigorously to improve their skills and physical fitness, and many aspire to achieve high rankings in the Association of Tennis Professionals (ATP) or Women's Tennis Association (WTA).