The application of large-scale Terraforming allowed the environment of many marginal worlds to be changed to accommodate humans. Most of these worlds were discovered during the Initial Wave of colonization but not settled due to their inhospitable atmospheres or climates. WIth Terraforming technology, these worlds were reconsidered for human habitation.
Resource-rich or geographically-located worlds were prioritized for the Terraforming process, particularly planets that required only a minimum of environmental tinkering. Such worlds became sources of raw materials for the First Colonies, and many Terraforming Wave colonies shared the wealth of their Inital Wave neighbors.