Granular materials are particle systems in which the sizes of the constituents are large enough that they are not subject to thermal motion fluctuations. Typical grain sizes range from micrometer up to tectonic scales. These materials are everywhere and the capability to handle, process, store and produce them is of paramount importance. From a fundamental point of view, the science of granular matter is very exciting and puzzling. While these materials are composed of simple elements that interact with known laws, their behaviors and properties are complex. Granular materials can flow, but with different hydrodynamic properties than classical fluids; they can support weight, but stress does not distribute as in a homogeneous solid.