The Green Card is a document confirming that your traffic insurance is valid in a foreign country. The Green Card is a compulsory document that is required for travelling outside the borders of the member states of the European Economic Area (except for Switzerland). It is recommended to have the Green Card while travelling within the borders of the member states of the European Economic Area, but your traffic insurance policy would also suffice.
It is compulsory to take the Green Card with you when you are travelling to the following countries
Albania, Andorra, Azerbaijan, Bosnia and Herzegovina, Belarus, Croatia, Israel, Iran, Morocco, Moldova, Macedonia, Serbia, Montenegro, Tunisia, Turkey, Ukriane, Russia, Great Britain.