Surface tension is a force that holds the surface of liquids together.
Surface tension depends on the nature of the liquid, the surrounding environment and temperature. Liquids were molecules have large attractive intermolecular forces will have a large surface tension.
Measuring surface tension provides data reflecting thermodynamics of the compounds tested, and reveals fundamental physicochemical properties associated with processes such as adsorption, hydrogen bonding interactions, and self-assembly.
Tensiometers allow the measurement of the force which is necessary to exert vertically on a ring, in contact with the surface of the liquid, in order to separate it from the surface, i.e. to draw up the film that has formed.