This textbook metamorphosed from notes that the author has been using to teach at four universities in Australia and New Zealand. The book treats the physical principles and design of wireless Internet of Things (IoT) systems from engineering perspective. IoT enables communication between people, between people and things, and between things. The book highlights the wide scope of sensors used in IoT - including RFIDs, smart mobile phones, home consumer devices, autonomous cars, utility meters, car park meters, robots, satellites, radars and wireless positioning systems. Three features render the book practically accessible. First, each chapter is organised in sections, each of which ends with a set of authentic review questions to motivate reflection. This is complemented by numerous worked examples in each section. Third, the book introduces two popular industry software packages for hands-on practice -- MATLAB(R) and CelPlanner(TM). With the growing popularity of softwarisation and cloudification, possessing expertise in these packages makes one useful to the industry. Parts of this book are taught in undergraduate curriculum, while the rest is taught in graduate courses. Both traditional and modern topics including C-RAN, network slicing, NFV, NB-IoT and 5G use cases in IoT are covered.