Capillarity

Capillarity, or capillary action, is the ability of a liquid to flow in narrow spaces without external forces. This phenomenon occurs due to the interplay of cohesive forces (molecules sticking to each other) and adhesive forces (molecules sticking to the walls of a container). For example, when a thin straw is placed in water, the water rises inside the straw due to adhesion to the straw's walls and cohesion between water molecules. Capillarity is important in various natural processes, such as how plants transport water from roots to leaves, as well as in everyday situations like a sponge soaking up liquid.