Surface tension is a physical property observed at the interface between two immiscible fluids, such as a liquid and a gas, or a liquid and a solid. It arises from the cohesive forces acting among the molecules within the liquid, which result in the surface layer experiencing a net inward pull. Because the molecules at the surface have fewer neighboring molecules to pull them in all directions compared to those in the bulk of the liquid, the net force results in the surface acting to minimize its potential energy. This characteristic explains phenomena ranging from the ability of certain insects to walk on water to the formation of droplets, making it a crucial consideration in fields like fluid dynamics and material science.