Beads， stones， seashells， paper， precious metals such as gold and silver， base metals such as iron have all been used as money. Today， money is printed on paper. A lot of countries use their own currency， with n ames such as dollar， pound， franc， ruble， yuan and so on. Since 2002， 18 of the EU members have replaced their national currencies by Euro notes and coins. If you want to pay for something in another currency, you have to change your money into the other money. If you want to travel outside your native country, you need to change your own country's money for the money of the country you are visiting. Most large banks sell foreign currencies. You can exchange money at a bank or at an office of a tourist agency Wherever you go, exchanging money puts you in touch with international finance, which is concerned with exchange rates between different currencies. Deciding the rate for the international exchange of money is one of the most complex aspects of international banking. Foreign exchange rates have significant impact on the economy of a country.