Professional tennis is a competitive sport where players compete in singles or doubles matches on various surfaces, including grass, clay, and hard courts. The sport is governed by organizations like the Association of Tennis Professionals (ATP) for men and the Women's Tennis Association (WTA) for women. Major tournaments include the Grand Slam events: the Australian Open, French Open, Wimbledon, and the US Open. Players earn rankings based on their performance in tournaments, which affects their eligibility and seeding in competitions. The game requires a combination of physical fitness, mental strength, and technical skill. Notable professional players include Roger Federer, Serena Williams, and Rafael Nadal.