Mastering Bitcoin

Book by Andreas M. Antonopoulos hosted on Github (also available for purchase in physical and digital forms).

Bitcoin is still in its infancy, and yet it has already spawned an economy valued at nearly $2 billion that is growing exponentially. Established companies like PayPal are considering adding bitcoin as a payment method, and investors are funding a flurry of new startups aiming to stake claims in a new industry that may rival the Internet in terms of scale and impact on daily life.

Not to mention the numerous retailers online that accept bitcoin directly, including Microsoft.