In the United States we have a floating currency. The government cannot raise or lower the US Dollar exchange rate directly. It cannot raise or lower the conversion rate by decree, for example, by declaring that “As of noon tomorrow, all US banks will sell Euros or buy Japanese yen for exactly so many dollars and so many cents.” But the Federal Reserve can and does change the Funds rate. When they increase the rate, interest rates rise a bit all across the US banking system. This has the ripple effect of reducing the overall supply of dollars, which makes the US Dollar stronger against other world currencies. Having a low dollar to euro exchange rate, for example, may not be entirely a bad thing for all Americans. We know that it makes daily life expensive for American tourists in Paris or Rome who must convert dollars to euros before buying a croissant or getting opera tickets. But, a cheap dollar in Europe makes American cars more of a bargain for Europeans to buy. European companies might be more likely to choose an American consultant or software company, because the price in dollars is now very affordable in Germany or France. Currencies trading experts know that it's important to be following trends and staying alert for potential increases or decreases in the inflation rate and the shrinking or rising money supply.