Twenty One Million

Everyone has an opinion about Bitcoin. Almost no one can explain it. *Twenty-One Million* fixes that - not with a lecture, but with a story. Four colleagues at a staid insurance company are handed a thankless assignment: decide, in one page, whether the firm should touch Bitcoin. Margaret, who runs risk and trusts no one with money after being burned once, fully intends to write *no*. To do it honestly, she has to understand the thing first — and so, one Thursday at a time, in the worst conference room in the building, she and three equally skeptical colleagues take Bitcoin apart on a whiteboard and try to break every piece. They start where everyone's confusion starts ("what *is* a coin?") and end up somewhere they never expected: convinced that a ledger no one controls is harder to cheat than the bank down the street. Along the way the book quietly teaches the whole machine - keys and signatures, the chain, mining, why nobody can print more, how to actually buy and hold it without losing everything, and how to spot the scams built to take it from you. It is the rare explainer that respects you enough to be honest about the costs as well as the magic. If you've read three articles about Bitcoin and still couldn't say what it really *is*, start here. Written by Ritesh Modi - a longtime blockchain educator and author of two books on smart-contract programming - whose philosophy is simple and severe: make a hard thing clear without making it any smaller than the truth allows.