According to International Tennis Federation (ITF) rules, tennis balls can be white or yellow. Yellow balls are easier to see on color TV. The official color of fluorescent yellow balls is “optic yellow”.
Older tennis fans will remember that white balls were used at most tournaments several years ago. In fact, Wimbledon started using yellow balls only in 1986.
There has been some debate on the “optic yellow” color of the tennis ball. Some have felt that tennis balls are green, and not yellow. But for the most part, tennis players and fans agree that the ball is yellow.
ITF allows the use of slower balls to increase participation in tennis. The slowest balls are red, followed by orange and green. These balls are not used in professional matches.