Why does international trade require a system of currency exchange?

International trade requires a system of currency exchange because different countries use different currencies, making it essential to convert one currency into another for transactions. This exchange allows businesses to accurately price goods and services across borders, facilitating trade. Additionally, currency exchange helps to manage risks associated with fluctuating exchange rates, ensuring that both buyers and sellers can transact with confidence. Without a currency exchange system, international trade would be cumbersome and inefficient.