In painting, photography, drawing, perspective is the technique and special effects in various ways of representation of three-dimensional scenes in the plane aimed at rendering of three-dimensional depth relationships in two dimensions. In simpler words, perspective is a way of creating of the illusion of spatial depth in the flat picture.
Traditionally, development of various types of perspective is studied through the analysis of icons.
In most modern drawings/paintings the linear perspective is used: the further the objects are from the viewer, the smaller they are drawn and the closer they are positioned to the so-called vanishing point or points, so that the (drawing of the) most remote objects completely disappear in the vicinity of these points.
Under the linear perspective the vanishing point or points are usually placed inside the painting with the illusion that it is "beyond" the drawing.
Under the reversed perspective, or inverse perspective, or Byzantine perspective the further the objects, the larger they are drawn. (The latter name is because thes kind of perspective is observed in earlier Byzantine and Russian Orthodox icons.) Technically, the vanishing points are placed outside the painting with the illusion that they are "in front of" the painting.
It is difficult to say now what were the intentions of the ancient iconographers, but a common interpretation is that the point of perspective is on the viewer, hence The Almighty looks upon him, rather than the viewer looks upon The Almighty.
Axonometric perspective is in between the two others: the relative sizes of depicted objects do not depend on the distance to the actual ones.
See also: Perspective distortion, Perspective transform, Desargues' theorem