Built on sand : the science of granular materials Grains seeds and powders Grain production Piles of grains The packing fraction Making contacts Manifestations of disorder Force chains Granular flow From sand castles to clay towers Sticky grains Fluids in granular materials Grains in a fluid. Granular materials are composed of macroscopic particles not molecules and yet they can assemble in disordered configurations such is present in glass and they exhibit both fluid like and solid like behaviors. This book gives a broad introduction to granular materials a fast developing field that impacts most science and engineering disciplines describing the different types and origins of grains natural and fabricated and explaining the physical properties of a pile of grains. All the physical concepts that have been investigated during the last thirty years are described and illustrated in simple terms