The process of heating a liquid until it changes to gas is called evaporation. This process occurs when the molecules in a liquid gain enough energy, typically through heat, to transition into a gaseous state. Evaporation happens at any temperature, not just at boiling point, as surface molecules can escape into the air. This process plays a crucial role in various natural phenomena, such as the water cycle, where water from oceans, rivers, and lakes evaporates and forms clouds. Understanding evaporation is essential for many scientific and environmental studies.