This book (AIR) is part of a series of 5 books, and will introduce you to the fundamentals of Iridology, a branch of Natural Medicine (NM) also known as Complementary Alternative Medicine (CAM). Iridology will help you to understand the constitution that you inherited from your parents (Genetics), and apply Nutrition and Lifestyle to prevent health conditions, or to treat the current ones. Although you can start studying any book in the series with no particular order, we suggest to start this book at the end, after you mastered other medical disciplines discussed in the series (MAT, AIR, NLP, BMG, APP). Medicine is a complex and fascinating topic, and we believe that this knowledge should spread around as much as possible. Health is so closely related to our life that we probably should not miss its key concepts, if we want to stay healthy.