It was one of the runners-up for the word of the year 2013 as chosen by Oxford Dictionaries; it has received a partial blessing from Ben Bernanke, the chairman of the U.S. Federal Reserve — but a warning from U.S. law enforcement agencies.

At one point it soared in value by 10,000 percent during 2013 until China's central bank dealt a blow to its fortunes.

Financial authorities, not to speak of economists, are sharply divided on whether the bitcoin is the currency of the Star Trek future or an empty promise with nothing to back it, so that it will and should fade away.