The beginning of the 2020's witnessed dozens of commercial astronauts fly to space on a variety of vehicles. These spacecraft included SpaceX's Crew Dragon, which supported the Inspiration4 and Axiom Space missions, Virgin Galactic's SpaceShipTwo, which supported several suborbital science flights, and Blue Origin's New Shepard spacecraft, which not only flew celebrities but also its fair share of commercial astronauts.  The story of this new breed of spacefarer has only just begun. As evidenced by these missions, commercial spaceflight has grown beyond passengers simply traveling to space just for the ride. With orbital flights involving commercial astronauts staying in space for several days and weeks, companies such as Sierra Space, Axiom Space and Blue Origin are preparing for the next steps in commercial space travel which include the construction of orbiting habitats.  But how will the opportunities for commercial astronauts develop, how will they be trained, and will this new group of astronauts evolve? This book describes how the commercial spaceflight industry is evolving, how it will continue to evolve as barriers to entry are reduced, competition grows, and costs are lowered, and how, because of these efforts, opportunities for commercial astronauts will increase.