Capillary action is the ability of a liquid to flow in narrow spaces without the assistance of external forces. This phenomenon occurs due to the combination of cohesive forces within the liquid and adhesive forces between the liquid and the surrounding material. For example, when a thin tube, like a straw, is placed in water, the water rises inside the tube due to these forces. This action is essential in various natural processes, such as the movement of water in plants. In plants, roots absorb water from the soil, and capillary action helps transport this water through xylem vessels to reach the leaves and other parts.