Terraforming is the process of altering a planet or moon’s atmosphere and environment in general to that of a liveable ‘earthlike’ environment (or within very similar tolerances, which appears to be a near galactic standard for intelligent life).
The process of terraforming is long and not inexpensive. But in the current climate of lost worlds and limited living space, has become a necessity to accommodate still growing Cal-Civ populations
Similarly the process of ‘Shagrilising’ a world is to make it closer to ideal than a terrformed world. This version of planetary alteration is usually seen on pleasure worlds or the retreats of some corporate magnates hidden hidey-moon. They often require a small level of upkeep – but preclude any unsatisfactory weather conditions and the like (or not – it all depends on the eco-engineers desire)