Osmosis is the process by which water molecules move across a selectively permeable membrane from an area of lower solute concentration to an area of higher solute concentration. This movement occurs in response to differences in osmotic pressure and aims to achieve equilibrium on both sides of the membrane. Osmosis is vital for maintaining cellular homeostasis and plays a significant role in various biological processes, including nutrient absorption and waste removal. It helps regulate the internal environment of cells and supports overall organism health.