The process by which molecules of water vapor in air become liquid water is called condensation. It occurs when the water vapor cools down and the molecules lose energy, causing them to slow down and come closer together. As they get closer, they start to attract each other more strongly, forming tiny droplets of liquid water. These droplets can then grow larger by combining with other droplets or by absorbing more water vapor. Condensation is an important part of the water cycle, as it returns water from the atmosphere to the Earth's surface. It is also responsible for the formation of clouds, fog, dew, and precipitation.