For tennis ball machines to shoot balls with perfect accuracy and at nearly 100 miles per hour, it takes a series of carefully calibrated parts working together. Here's what it looks like inside.

There’s a lot more to tennis than hitting a ball back and forth on a court ... apparently does kangaroo jumps in the dressing room, running inbetween ladder rungs is a popular method for ...

A tennis ball is made of hollow rubber and covered with felt ... in width; each doubles alley, running the length of the court, is 4 feet, 6 inches wide. The court is divided into two equal sides by a ...