Terraforming is changing a planet or large natural satellite that we cannot live on at present without spacesuits and similar technology. The idea is to change it so some life from Earth could exist there. It would need a suitable atmosphere (air), heat, and water. "Paraterraforming" or "worldhousing" is a variant of terraforming that would involve building domes over the majority of a planet or moon.
It is arguable that we have already succeeded in terraforming right here on Earth. Thanks to modern technology, humans can now thrive in places that should be impossible to live in such as deserts and the Arctic.
A related concept is paraterraforming or worldhousing which would involve constructing greenhouse-style geodesic domes and similar structures to cover most of, if not the entire surface of the planet or moon.
- Oberg, James Edward 1981. New Earths: restructuring Earth and other planets. Stackpole Books, Harrisburg, PA.