Osmosis is the spontaneous net movement of solvent molecules, typically water, through a selectively permeable membrane from a region of high solvent concentration to a region of low solvent concentration. This movement is driven by the differential concentration of dissolved solutes, as water tends to equilibrate the solute concentration across the membrane. The process is fundamental to biological systems, governing the regulation of internal cellular fluid balance and the movement of substances within tissues. The rate and direction of osmosis are dependent on the permeability of the membrane, the solute concentration gradient, and the surface area involved.