This book proposes a sound and realistic exploration on the topic of terraforming. Often used as the narrative premise in science fiction novels, terraforming is the process by which an uninhabitable planet might be converted into one capable of supporting life. This book presents what is physically possible today and hints what might conceivably be put into practice in the next several hundred years. The author works within the realms of current technology and known physics, although speculation on future advancements inevitably enters the discussion. Introductory chapters establish why terraforming will be of great benefit to human kind, and also put in place the basic physical arguments necessary to the terraforming process. The following parts look at various proposals that have been made for terraforming the planets Mars and Venus. The book concludes with a glimpse to the much deeper future when humankind will explore and colonize the outer solar system and possibly the newly discovered exoplanets.