Perspective: Any method by which a three-dimensional space is represented on a flat surface. Linear, aerial (or atmospheric), isometric, cabinet, and reverse perspective are most commonly used.
The air that we see in the paintings of the old masters is never the air that we breathe. - Edgar Degas
Having perspective in visual design, is creating visual context for the viewer. By creating the appropriate perspective you are able to depict a scene with greater realism, and hopefully creating more than just a visual experience. When an artist has the ability to create great perspective the viewer can ofter feel drawn or pulled in to the artwork, or even that they are placed within the artwork. Each medium of art has many was of creating perspective, but it is a true skill to develop overwhelming real perspective.