High Quality Content by WIKIPEDIA articles! Classical and quantum mechanical views of conductivity have both described the movements of electrons in a metallic solid. The free electron gas that is present in metallic solids is the reason for an important property of all metals: conductivity. This article will discuss the theory of conduction, specifically the theory of classical conduction whose defects were explained by the quantum theory. The modifications that the quantum theory adds to classical conduction not only explains the flaws that arose in the classical theory, but also adds a new dimension to conduction that is currently leading to new developments in the physics world.