The phenomenon that describes the movement of water through a selectively permeable membrane is called osmosis. This process involves the passive diffusion of water molecules from an area of lower solute concentration to an area of higher solute concentration, aiming to equalize solute concentrations on both sides of the membrane. Osmosis is essential for maintaining fluid balance in cells and is crucial for various biological functions, including nutrient transport and waste removal. It plays a significant role in cellular homeostasis and overall organism health.