The world of cyber currency has experienced explosive growth in recent years, accompanied by numerous controversies and misunderstandings about what it is, how it works, and how it relates to the underground economy and illegal activities such as money laundering, tax evasion, and human trafficking. Many illegal or malicious activities are paid for with cyber currencies, and this book covers those applications. But cyber currencies also have many legitimate, constructive applications, which are explained in clear, plain English, without embellishment or exaggeration. An authoritative and thought-provoking reference for readers seeking a greater understanding of all aspects of alternative cyber currencies, this encyclopedia discusses economic history, international trade, current controversies, and the impact on the wider underground economy. It peels back layers of jargon and obfuscation, giving each topic individual attention to show how it works and contributes to the whole.