Surface tension is a physical property of liquids that arises from the cohesive forces between liquid molecules. It is defined as the energy required to increase the surface area of the liquid by a unit area. At the molecular level, surface tension occurs because molecules at the surface of a liquid experience a net inward force: they are attracted more strongly to the molecules beside and below them than to the air above. This results in a "skin-like" effect on the surface of the liquid.
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