x, y, z are variables commonly used in mathematics and science to represent unknown values or coordinates in a system. In a two-dimensional space, x typically represents the horizontal axis, while y represents the vertical axis. Together, they help define the position of points on a graph. In three-dimensional space, a third variable, z, is added to represent depth. This allows for a more comprehensive understanding of spatial relationships. The combination of x, y, and z coordinates is essential in fields such as physics, engineering, and computer graphics for modeling and analyzing objects in space.