Osmosis is a fundamental physical process defined as the spontaneous net movement of solvent molecules through a selectively permeable membrane from a region of lower solute concentration to one of higher solute concentration. As a core concept in physical chemistry, biology, and engineering, it investigates the thermodynamic principles and kinetic factors governing solvent transport driven by differences in chemical potential, highlighting the role of membrane properties and solute-solvent interactions, with broad significance in cellular function, water purification, and energy conversion.