Bitcoins have no intrinsic value. But since they were introduced to the world in 2009 by inventor Satoshi Nakamoto (a pseudonym), they have turned into a billion-dollar market and have been designated a currency by the U.S. government. Since the days when stones and shells were recognized as a means of payment, currency has taken many forms. What makes bitcoin a currency is what it does, not what it is. "To the extent it looks, walks and acts like a duck, this 'duck' is a currency,"