A vapor is the gaseous state of a substance that originates from, or is closely associated with, the liquid or solid phase of that substance. This phase transition occurs when the energy imparted to a material molecules overcomes the intermolecular forces holding the substance in its condensed state, allowing them to escape into the surrounding environment. The pressure exerted by these gaseous molecules above the liquid or solid surface is known as vapor pressure, which is characteristic of the material at a given temperature. The specific nature of a vapor—whether it is saturated (at equilibrium) or supersaturated—depends on the rate of energy transfer and the environmental conditions, defining its thermodynamic properties and behavior in a closed system.