I work in finance. The vast majority of currency work is the following: repatriation of profits by a company. Let's say coca cola needs to repatriate their profits from Thailand to America. If the exchange rate is bad it could wipe out their profits, so their corporate treasury people will trade the currency at a price point which ！accounts for market fluctuations, tax liabilities which might arise out of changing their currency, inflation etc. This is known as currency risk. if a company needs materials or needs to buy commodities but the supplier only accepts a particular currency, then they need to acquire that cash. They usually arrange this with their financial institution.