This chapter introduces the fundamental principles of bulk solids storage, flow, and handling, establishing their relevance across a wide range of industrial sectors including mining, agriculture, manufacturing, food processing, and pharmaceuticals. In contrast to fluids, bulk solids display complex mechanical behaviour arising from particle interactions, friction, cohesion, consolidation, and environmental influences. A lack of understanding of these characteristics has historically resulted in flow obstructions, product degradation, and, in severe cases, structural failures of bins and silos, highlighting the economic and safety consequences of inadequate design.