Cohesion (from the Latin cohaesus - connected, linked) is the adhesion of molecules (atoms, ions) of a physical body under the influence of attractive forces. These are the forces of intermolecular interaction, hydrogen bonding and (or) chemical bonding. They determine the totality of physical and physicochemical properties of a substance: state of aggregation, volatility, solubility, mechanical properties, etc. The intensity of intermolecular and interatomic interaction (and, consequently, the force of cohesion) decreases sharply with distance. Cohesion is strongest in solids and liquids, that is, in condensed phases, where the distance between molecules (atoms, ions) is small - on the order of several Å. In gases, the average distances between molecules are large compared to their sizes, and therefore cohesion in them is negligible. A measure of the intensity of intermolecular interaction is the cohesion energy density. It is equivalent to the work of removing mutually attracted molecules or atoms to an infinitely large distance from each other, which practically corresponds to the evaporation or sublimation of a substance. According to TSB.