Every currency has its price which is called the exchange rate. It shows how many units of one currency are equivalent to one unit of another currency. The price of a given currency depends on economic condition of the country which emits it. Even slight negative or positive trends or events in economy of a certain country make its currency less or more expensive in relation to other currencies. But economic conditions are not the only factor which has effect on the price. Market expectations, forecasts and speculations drive enormous amounts of currency units from account to account and make the exchange rate fluctuate very often - every minute or sometimes even every second. Such fluctuations allow traders to buy currency units at lower rates and sell them when the rates get higher. The difference between the buying and selling prices is a trader's profit.