The digital currency founded by Satoshi Nakamoto in 2009 challenges everything we've come to accept about money, financial institutions, and even government. The currency is anonymous and can be traded internationally-without the fees, government regulation, and oversight by banks and government-backed securities. But Bitcoin is not without risk-the currency's value has fluctuated wildly since inception, and 400 billion suddenly disappeared overnight with the fall of Mt. Gox. Bitcoin: Everything Y.