This is a modern book in solid state physics that should be accessible to anyone who has a working level of solid state physics at the Kittel or Ashcroft/Mermin level. The key point of this book is the development of classic topics in a way that makes it easy to present current topics. The book starts with the non-interacting electron gas and develops in great depth such topics of immense currency as the Kondo problem, Bosonizations, local moments in metals, quantum phase transitions, insulator-superconductor and insulator-metal transitions, and the quantum Hall effect. The presentation of these topics starts from the beginning where no prior knowledge is assumed. Hence, this book should be extremely useful to those seeking an introduction tot he practice of modern solid state physics.