Linear perspective is a mathematical system for creating apparent depth and volume on a surface. Linear perspective has several aspects:
One-point perspective requires a single vanishing point on the horizon line to which all lines receding into space converge. If a cube is depicted, the viewer will face a flat plane of the cube. Two-point perspective requires two vanishing points on the horizon line. If a cube is depicted, the viewer will face an edge of the cube. Three-point perspective requires three vanishing points - usually two of the vanishing points are on the horizon line and a third is above or below the horizon line.
One-point perspective
One-point perspective
Two-point perspective
Two-point perspective.
(In many cases, the vanishing points of 2+ point perspective will not be within the picture format.)