The process when water changes from a liquid to a gas is called "evaporation." This transition occurs when molecules at the surface of the liquid gain enough energy, typically through heat, to break free from their bonds and enter the gaseous state. Evaporation can happen at any temperature, although it occurs more rapidly at higher temperatures. It plays a crucial role in the water cycle, contributing to the formation of clouds and precipitation. Additionally, evaporation has practical applications, such as in cooling systems and in the drying process of various materials, making it an essential natural phenomenon.