A European-style option is an option which can only be exercised at expiration under its contract rules. This differs from American-style options, which allow exercise before expiration. With otherwise identical terms, the extra exercise right cannot reduce theoretical value, so a European-style option can be worth less. Many index options use European exercise, but the exact series must be checked.
Exercise style does not prevent selling the option to close while its market is open. Check last trading time, settlement method and the price used for settlement; European style does not by itself establish those terms.
