We survey inhomogeneous materials, both microscopic and macroscopic. We elucidate the conditions under which the transport properties of a microscopically inhomogeneous material become local so that the problem of determining macroscopic properties becomes the same as for macroscopically inhomogeneous materials. We review percolation briefly, survey the basic theoretical tools for dealing with inhomogeneous materials, and describe a few typical theoretical results. Finally, we review the results of our studies of metal‐non‐metal transitions in microscopically inhomogeneous materials.