This book is published in cooperation with the OSA Foundation and CSIC. Light is an element that draws together many areas of human knowledge: physics, chemistry, biology, astronomy, engineering, and art. Moreover, optical phenomena and the technologies based on them are widespread in our daily lives. However, it can be difficult to understand or explain these phenomena. What is light? Where are optics and photonics present in our lives and in nature? What lies behind different optical phenomena? What is an optical instrument? How does the eye resemble an optical instrument? How can we explain human vision?This book, written by a group of young scientists, answers these questions and many more to help you to get to know the exciting world of optics and photonics. It is intended for the general public, with an emphasis on students at all levels of secondary education. A variety of easy-to-follow experiments related to different optical phenomena and technologies are presented. All of them are preceded by an explanation of the concepts and accompanied by numerous illustrations and curiosities. All of it is meant for you to have fun with optics and photonics!