What is the standard color of a tennis ball used in professional tournaments? The answer is yellow.
Professional tennis balls are usually fluorescent yellow, often called optic yellow. The color was introduced because research showed it was easier for television viewers to see than the white balls traditionally used in tennis. The International Tennis Federation approved the change in 1972, and yellow balls quickly became standard.
The familiar ball is not simply a colored rubber sphere. It has a hollow, pressurized rubber core and a fuzzy felt covering, which affects its speed, bounce, and flight through the air. The felt also helps players apply spin.
People sometimes call the ball green because optic yellow can appear greenish under certain lighting, and the color remains mildly controversial in everyday perception. The ITF also permits white balls, although fluorescent yellow dominates professional competition. Wimbledon continued using white balls until 1986, making the modern yellow ball a relatively recent standard rather than an ancient tradition.