Evaporation's the slow vaporization of a liquid and the reverse of condensation. A type of phase transition, it's the process by which molecules in a liquid state (for example water) spontaneously become gaseous (for example water vapor). Generally, evaporation can be seen by the gradual disappearance of a liquid from a substance when exposed to a significant volume of gas. Vaporization and evaporation however, aren't entirely the same processes. For example, substances like caesium, francium,… (More on Evaporate)