A decade has passed since Bitcoin's invention. Bitcoin and its underlying blockchain technology, so the promise goes, is poised to do for value what the internet has for information. The internet has enabled the easy and immediate transfer of practically all and any information. Blockchain technology has the potential to make a variety of processes much more efficient by enabling the transmission of value by a protocol without the need for expensive intermediaries. But is the mere potential enough to make the bold claims around the blockchain hype realistic? What has actually evolved during the last ten years and what is likely to happen in the next decade?

The aim of this book is to demystify blockchain and its surrounding hype. We give readers a basic knowledge of the technology involved and explain its different aspects so that its potential and implications can be fully appreciated, and the reader can make their own differentiated assessment of when the use of blockchain technology makes sense and when it does not. Our aim is to provide a balanced overview of the current status of blockchain. However, how society will embrace or reject the various options that blockchain technology offers is still unclear. A grounded discussion of its socio-economic implications has to include some speculation of future developments. We engage in some of this speculation but also explain real examples of blockchain implementations, which we hope enables the reader to distinguish between actual applications, realistic potentials and mere fantasies.

Centralization constitutes an integral paradigm in modern societies. Most of the services that we interact with – even interaction between individuals – is enabled and processed by some kind of intermediary. Whether this is Facebook for communicating with friends, Google for finding information on the internet or a commercial bank for taking out a loan. Centralized architectures ensure the control and efficient management of a service provider over the access to a service. This is, however, the perspective of the service provider. The centralization of interactions through intermediation makes us dependent on them and we have to trust that they will do what we ask for. Moreover, these structures inherently produce costs and other disadvantages for the individual. These costs can be the personal data that has been voluntarily submitted to Facebook's servers, which is (almost) freely utilized and monetized.