This book is not an advertisement or invitation to buy into the bitcoin currency. Far from it. The value of bitcoin is likely to remain volatile, at least for a while; the bitcoin network may yet succeed or fail, for whatever foreseeable or unforeseeable reasons; and using it requires technical competence and carries risks that make it unsuited for many people. This book does not offer investment advice, but aims at helping elucidate the economic properties of the network and its operation, to provide readers an informed understanding of bitcoin before deciding whether they want to use it.