For much of its early history, tennis was an amateur sport. However, in the 1920s and 1930s, professional players began to emerge, touring the world and playing exhibition matches. The sport's popularity continued to grow, but it wasn't until 1968, with the advent of the Open Era, that tennis officially became a professional sport. This change allowed both amateur and professional players to compete in all tournaments, significantly raising the level of competition and the sport's global profile.