The rise of the internet as a global communication platform opened new possibilities of communication, and fundamentally changed the way people interact. In that regard, one of the most interesting developments is the rise of digital currencies, a fairly new phenomenon that promises to revolutionize the way we think about finance. This book will analyze the concept of digital currencies, focusing on Bitcoin, the most prominent digital currency to date. It will start with a brief history and definition of the concept of money, followed by a deeper analysis of digital currencies in general. The last two chapters of the book will focus on Bitcoin, describing in detail the currency and making an analysis of its strengths, weaknesses, opportunities and threads.