Capillary action is the spontaneous movement of a liquid through narrow spaces or small tubes without external forces like gravity. It occurs when adhesive forces between the liquid and the surface are stronger than the cohesive forces within the liquid, allowing the liquid to climb up or fill narrow spaces. This phenomenon is driven by surface tension and intermolecular forces and can be observed when water rises in a thin straw or when a paper towel absorbs liquid. Capillary action is essential in natural processes such as water transport in plants and has practical applications in various industrial and everyday activities.
