Mobile phones, public transport smart cards, security cameras and GPS systems in our car – we are surrounded by digital devices. They track us, guide us, help us, and control us. The book Check In / Check Out. The Public Space as an Internet of Things shows us how our digital and physical worlds are rapidly merging into an Internet of Things. We’ve checked in, but can we still check out? As our information society is entering a new phase, we no longer surf on the net, we live in the net. While we are travelling, working and shopping, we continuously check in and check out. These digital transactions show governments and companies where we are and what we are doing. We have become moving dots on a digital map. In exchange for this loss of privacy, we get access to information, spaces and goods. But what are the risks? And what price will we pay? The authors of Check In / Check Out – researchers from the Dutch science and technology think tank The Rathenau Instituut – demonstrate how we should start managing our digital identity, by providing a set of design principles for this Internet of Things. These design principles are aimed to balance the power struggle between governments, businesses and the users of digitized public space. Protecting privacy is just one side of the story, more important is the empowerment of users. Questions answered are: what can we do to make technology work for users and not against them? When can the right to privacy be revoked because the security stakes are too high? How can users profit from their personal data? Should governments allow their citizens more control over their digital identities? The international case studies in the book show how countries deal with the digitalized public space in their own particular way. The book includes case studies on Japan, China, the United States and Europe. The authors focus primarily on the Netherlands, a country with high ambitions on IT projects, combined with a lively public debate on any failures. An example of this is the smart cards used in public transport systems. These cards were first introduced in large Asian cities, were the technology had to be proven to be safe and well functioning before the old system was discarded. The Dutch public transport card, however, was forced upon its users. Detailed personal and travel data are being collected and used by transport companies, marketers and for police investigations. From the ensuing and evolving public controversy, lessons can be learned. The artfully designed book Check In / Check Out closes the gap between the physical and the digital world in that it contains an innovative technology whereby the illustrations in the book can be read by smart phones which connect readers to the latest information, audio fragments and videos on the web. Welcome to the Internet of Things in Check In/ Check Out!