Over the years, numbers on tennis balls have caused much speculation about its purpose The International Tennis Federation, the governing organization that establishes the rules for balls and other equipment, provides detailed specifications for its manufacture, but putting numbers on the balls is not one of them.
Types of balls
The ITF establishes three types of balls for games on different types of court surfaces. The organization uses the numbers to identify the different types. The number 1 type is for the game in courts of slow surfaces like clay. Type 2 are for medium speed courts, such as acrylic and carpet, and type 3 are for fast courts such as artificial and natural grass. Contrary to what some people believe, the numbers on the balls do not indicate their type. There are only three numbered types and the numbers above three appear in several of them.
The reason for numbers on tennis balls turns out to be very simple, according to Whitney Kraft, tennis director of the United States Tennis Association's Billie Jean King National Tennis Center. If you have ever played tennis on a court next to others, you know how easy it can be for your ball to get out of your court and enter another. The numbers, according to Kraft, are to help players identify them when this happens.
A pack of tennis balls usually contains three. All of the packages have the same number on them, along with the name of the manufacturer. It is a common practice for players to record the mark and number of the balls before they start playing so that they can easily identify them if they accidentally end up in another court, mixed with other balls.
Novice players may not understand the importance of being able to identify their balls. Most manufacturers package them in a pressurized tube or can to prolong their shelf life. However, once the package is opened, they begin to lose their boat. The more you use, the less effective it becomes. Many veteran players use a new pack of them each time they play. If you're playing with new balls and the players on the next court are using older, less effective balls, you'll want to be able to find your own ball instead of an old battered one if they get mixed up.