Tennis is a game played between two people. But long before they meet on a court, each of them will have put in countless hours of practice. However, not all practice is created equal. It is not always possible to have a partner at all times, and discrepancies in skill level and experience may be problematic. Also, there is a technical component to tennis that must be practiced in isolation, without the variables of another player. This is where the tennis ball machine comes in.