This book covers aspects and achievements of the baryonic (star and gas) component of galaxy halos as presented at the successful conference "On the Origin (and Evolution) of Baryonic Galaxy Halos," held on the Galapagos Islands, Ecuador, March 13-17, 2017. It can be regarded as a compendium of the prominent results in this field. The main focus is the latest simulations and observations of galaxy halos. This compendium is recommended to researchers, and advanced students, as it contains peer-reviewed high quality papers that will meet their scientific needs and help to initiate new research directions. Everything described in this book is the result of a truly collective effort from the participants of the Galapagos conference.