**Where am I?**

Most people who write 3D programs think in terms of a 3D coordinate system with three axes.

A specific point or location in that coordinate system is specified by three coordinate values.

The axes are typically thought of as:

- A horizontal axis
- A vertical axis
- An axis that is perpendicular to a plane that goes through the horizontal and vertical axes.

Typically those axes are thought of as being represented symbolically by:

- X
*(horizontal)* - Y
*(vertical)* - Z
*(perpendicular to X and Y)*