Linear Perspective
The geometric effect by which parallel lines receding from the viewer appear to converge toward a point.
In depth
Linear perspective is a property of projection, not of lenses: any camera at a given position produces the same convergence. It is the most powerful depth cue available and the easiest to exploit, since almost every built environment supplies parallel lines. Its strength depends on how close the camera is to the converging lines.
Examples in practice
Standing in the centre of a railway track makes the rails converge steeply, pulling the eye to the vanishing point.