A surface, as the term is most generally used, is the outermost or uppermost layer of a physical object or space. It is the portion or region of the object that can first be perceived by an observer using the senses of sight and touch, and is the portion with which other materials first interact. The surface of an object is more than “a mere geometric solid”, but is “filled with, spread over by, or suffused with perceivable qualities such as color and warmth”.

Depending on the properties on which the emphasis is given, there are several non equivalent such formalizations, that are all called surface, sometimes with some qualifier, such as algebraic surface, smooth surface or fractal surface.

The concept of surface and its mathematical abstraction are both widely used in physics, engineering, computer graphics, and many other disciplines, primarily in representing the surfaces of physical objects.

The concept also raises certain philosophical questionsfor example, how thick is the layer of atoms or molecules that can be considered part of the surface of an object ,