Book excerpt: The last century has been characterized by the development of information theory and the consequent transformative impact of new technologies on societies around the world. It seems likely that the tremendous progress in nanoscience – the ability to manipulate microscopic systems at the level of a single atom – and the emergence of quantum information science, will be the key components of the next revolution; that of the new quantum technologies. Indeed, the ability to manipulate and control quantum systems has already found a variety of potential applications, ranging from the development of molecular nanoscale machines which exploit quantum coherence for their functioning, to metrological schemes where quantum effects are used to enhance the accuracy of measurement and detection systems to achieve higher statistical precision than is possible using purely classical approaches. This book presents the proceedings of the Enrico Fermi Summer School on Quantum Simulators (Course 198) held in Varenna, Italy, 22-27 July 2016. Topics covered included: cold atoms in optical lattices; trapped ions; solid state implementations; quantum many-body physics; quantum photonics; hybrid quantum systems; and transport phenomena. The book will be of interest to all those whose work is connected to the rapidly growing field of quantum technologies.