An exchange rate is the ratio at which two currencies are traded. The exchange rate is comprised of a base currency and a counter currency. In a direct quotation, the foreign currency is designated as the base currency and the counter currency is the domestic currency. In an indirect quotation, the domestic currency is designated as the base currency and the counter currency is the foreign currency.
The spot exchange rate is the exchange rate at which a currency can be delivered immediately. The closing rate is the spot exchange rate at the end of a reporting period.