The z-axis is one of the three axes in a three-dimensional coordinate system, alongside the x-axis and y-axis. While the x-axis typically represents horizontal movement and the y-axis represents vertical movement, the z-axis adds depth. This means that when you visualize a point in 3D space, the z-axis helps you understand how far back or forward that point is from the viewer. In practical terms, the z-axis is crucial in various fields, such as computer graphics, engineering, and architecture. For example, in 3D modeling, artists use the z-axis to position objects in a way that creates a realistic sense of space and perspective.