A currency in the most specific sense is money in any form when in use or circulation as a medium of exchange, especially circulating banknotes and coins. A more general definition is that a currency is a system of money (monetary units) in common use, especially for people in a nation.
The first region of the world to use an industrial facility to manufacture coins that could be used as currency was in Europe, in the region called Lydia (modern-day Western Turkey), in approximately 600 B.C. The Chinese were the first to devise a system of paper money, in approximately 770 B.C.