European options are those which can be exercised by the option holder only on the expiration date.
Options vary in style: European option (European style) and American option (American style). The main difference between them is that they have different expiry conditions.
It can be executed for a very limited period of time around the expiry date. It is formally considered that this is the day defined as the expiration date of options contracts. However, the practice of placing orders and the reconciliation procedure predetermine a slightly wider range, which still fit into the number of hours, which do not greatly expand the horizons.