Between 1876 and 1913, gold was the standard of currency (each currency was convertible into gold at a specified rate). When World War 1 began in 1914, the gold standard was suspended. Right now, each country has their currency. If I am traveling to Singapore, I can pick up some Singapore dollars from the airport that I can use during my time there.
In 2009, Bitcoin was introduced. Some people have described Bitcoin as a virtual currency. What is Bitcoin? How does it work? Do you think it can eventually replace the paper currency? What do you think will happen to the dollar if Bitcoin replaces paper currency?