What is it called when a gas changes to a liquid?

Condensation is the scientific term used to describe matter that changes from a gas state into a liquid state. The most common example of condensation is steam collecting on the lid of a boiling pot of water.

Condensation is a naturally occurring physical phenomena that plays an important role in the Earth's water cycle. Without condensation, the water that evaporated into the atmosphere would remain there indefinitely. The condensation of evaporated water on Earth promotes cloud formation, and allows for the redistribution of water across Earth's biomes. Condensation and evaporation can occur in compounds and elements other than water, although water is the most commonly occurring example in nature.