Linear Perspective is the most basic form of perspective in which all objects with faces parallel to the horizon, appear to converge in the distance at a single point on the horizon (the vanishing point).
To learn what on Earth this possibly means, grab yourself:
- a few sheets of 18" x 24" paper
- a pencil
- a straight metal ruler
- a white mars plastic eraser
and dare follow me to the next step.
Step 1: Vanishing horizons.
Now, if you were to stare straight ahead at the horizon, the point on the horizon directly in front of you would be considered the vanishing point. It's called the vanishing point since all objects seem to vanish towards it as they go back into the distance.
Step 2: A single point. A single perspective.
In other words, if there was a cube between you and the horizon, the face of the cube closest to you would have two horizontal lines parallel to the horizon. In fact, everything viewed in this perspective must have horizontal lines parallel to the horizon.
If horizontal lines are no longer parallel, you have just gained a whole new perspective (but lets not worry about that for now).