Question: Why are balls different color in racquetball?
About the article "Racquetball", section "Ball Colors".

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The European Racquetball Championships are organized every two years by the European Racquetball Federation (ERF), since 1981, to determine the strongest national racquetball teams and individual male and female players in Europe. 
The Italy national racquetball team represents the Federazione Italiana Racquetball in racquetball international competitions.
Is a member of the European Racquetball Federation and International Racquetball Federation. 
France national racquetball team represents the Fédération Française de Racquetball in racquetball international competitions.
It is a member of the European Racquetball Federation and International Racquetball Federation.  
Racquetballs are manufactured in a variety of colors such as blue, green, purple, black, red, and pink, and some are for specific purposes (e.g., outdoor play and indoor play), but the differences are unlikely to make much difference for recreational play.
Beginners are recommended to use a blue ball by Penn, Ektelon, or Wilson.
The blue ball is the most commonly used and it is the most neutral ball for average speed and accuracy of contact.
Green balls are similar to blue balls.
In the USA the main choices of ball are blue and green for tournament play.
In some cases the International Pro Racquetball Tour (IRT) will use a purple Penn HD ball as the official ball.
A black ball is often used in tournaments for senior players because the ball is designed to be slower moving and allows for longer rallies.
The red ball is the fastest in production and they are known as Red Ektelon Fireballs.
This ball is heavier and allows for a quicker pace.
The pink ball tends to be the favorite of most recreational players and even some pro level players.
This pink ball allows for the highest level of visibility due to the bright pink color.
Also, the speed and durability of the ball is very close to that of the blue and green.
Finally, the pink ball was created to support breast cancer research and the manufacturers of the ball Wilson, donate $1.00 to the breast cancer awareness association every time a package is sold.
Balls do break occasionally, and will lose their bounce over time even without breaking.
To keep balls around for a long time it is best to keep them in a room temperature setting and keep them out of extreme cold or heat because this will cause the balls to become less effective and lose their bounce.
Bowling balls vary, depending on the type of bowling game.
Ten-pin balls are large, up to 27 inches in circumference (approximately 8.59 inches diameter), and have as many as twelve holes, typically three holes.
The balls come in various weights from 6 to 16 lbs, with the size and spacing of the finger holes often smaller on lighter balls to accommodate smaller hands.
Different kinds of balls are available for different styles of bowling.
There are balls for hook shots and balls for bowling straight.
The bowling balls meant for hook shots have different core shapes and different chemical covers.
There are a few types of chemical covers that allow a bowling ball to hook more.
One of these types of covers is a resin cover.
This resin cover is designed to move and absorb the oil on the lane to create a path for the bowler where there is less oil, increasing the amount of hook of the bowling ball.
Balls for other games vary, e.g., candlepin balls which fit in the palm of the hand need no holes.
Unlike most sports, the ball can be different weights based upon the player.
All bowling centers provide bowling balls (house balls) - their usage is included in the bowling fee.
For ten pin bowling, the center will provide a fleet of house balls in varying weight and standard grip sizes while idle lanes have empty ball return racks.
Customers that use house balls will pick a ball that fits from the house ball fleet and place it on the ball rack at the designated lane.
When done, the customer should return the house ball to the house ball racks.
In small-ball games, each ball return contains a quantity of house balls — usually in at most one or two color patterns.