Investment management firms (who typically manage large accounts on behalf of customers such as pension funds and endowments) use the foreign exchange market to facilitate transactions in foreign securities. For example, an investment manager bearing an international equity portfolio needs to purchase and sell several pairs of foreign currencies to pay for foreign securities purchases.
The increasingly asymmetric relationship between the currency markets and national governments represents a classic autonomy problem. The “trilemma” of economic policy options available to governments are laid out by the Mundell-Fleming model. The model shows that governments have to choose two of the following three policy aims: (1) domestic monetary autonomy (the ability to control the money supply and set interest rates and thus control growth); (2) exchange rate stability (the ability to reduce uncertainty through a fixed, pegged, or managed regime); and (3) capital mobility (allowing investment to move in and out of the country).
The foreign exchange market is the "place" where currencies are traded. Currencies are important to most people around the world, whether they realize it or not, because currencies need to be exchanged in order to conduct foreign trade and business. If you are living in the U.S. and want to buy cheese from France, either you or the company that you buy the cheese from has to pay the French for the cheese in euros (EUR). This means that the U.S. importer would have to exchange the equivalent value of U.S. dollars (USD) into euros. The same goes for traveling. A French tourist in Egypt can't pay in euros to see the pyramids because it's not the locally accepted currency. As such, the tourist has to exchange the euros for the local currency, in this case the Egyptian pound, at the current exchange rate.