The European session refers to the trading hours in the foreign exchange market that coincide with the business hours in Europe. It typically starts at 8:00 AM GMT (or 9:00 AM CET) and ends at 4:00 PM GMT (or 5:00 PM CET). During this time, major financial centers in Europe such as London, Frankfurt, and Paris are active and the trading volume is usually high, making it a key period for forex trading activity.