Currency : How are currency prices determined?

How are currency prices determined?
Currency prices are affected by a variety of economic and political conditions, but probably the most important are interest rates, international trade, inflation, and political stability. Sometimes governments actually participate in the foreign exchange market to influence the value of their currencies. They do this either by flooding the market with their domestic currency in an attempt to lower the price or, conversely, buying in order to raise the price. This is known as central bank intervention. Any of these factors, as well as large market orders, can cause high volatility in currency prices. However, the size and volume of the FOREX market make it impossible for any one entity to drive the market for any length of time.