Tennis Subdivision is a term used to describe the different levels of play in the sport of tennis. It is divided into three categories: beginner, intermediate, and advanced. The beginner level is referred to as 'SET' (3 letters). This level is for those who are just starting out in the sport and need to learn the basics. Intermediate players are those who have some experience and are looking to improve their skills. Advanced players are those who have mastered the fundamentals and are looking to compete at a higher level.