In basketball, there are two main types of defense: zone and man to man. When referring to zone defenses, the "X-Y-Z" format is used. This shorthand notation refers to the position of the players in three layers: the X-, Y-, and Z-layers.
Sorting players into respective "layers" helps organize a defense because it creates a quick and easy way to express how many players should be in each layer of defense. Some examples of the X-Y-Z zone format include:
The X-layer always refers to the area of the frontcourt that is farthest from the baseline, while the Z-layer contains the set of players closest to the baseline. Not all three letters need to be used to describe a formation. For example, the 2-3 zone only uses two layers, but it is still a well known and commonly understood formation.