Sediment transport is the suite of physical processes governing the entrainment, movement, and deposition of particulate material (clastic or biogenic) by a transporting medium, typically water, air, or ice. In fluvial and coastal systems, it is controlled by fluid shear stress, turbulence, grain size, density, and bed roughness, and occurs as bedload, suspended load, or wash load. Sediment transport underpins channel and shoreline morphodynamics, stratigraphic architecture, and landscape evolution, and is commonly quantified using transport equations (e.g., Shields parameter–based formulations) and numerical models that couple hydrodynamics with sediment entrainment, advection, diffusion, and deposition.