Introduction to 3D Coordinate Space
In 2D, every point is described by two coordinates . Moving into three-dimensional space simply adds a third axis — the -axis — perpendicular to both the - and -axes. Every point in 3D space is then described by an ordered triple .
A system that locates points in space using three mutually perpendicular axes: the -axis, -axis, and -axis. A point is written as , where each value measures the signed distance from the origin along its respective axis.
Think of the origin as the corner of a room: the -axis runs along one wall, the -axis along the other wall, and the -axis runs straight up toward the ceiling.

All the familiar 2D formulas — distance, midpoint, gradient — have direct 3D counterparts. The key idea is simply that you now have a third coordinate to account for in every calculation.