Electricity
Most countries in Europe have an official mains of 230 Volts and 50 Hertz. The plug is standardised and used in all countries except - of course - on the islands England, Ireland, Cyprus and Malta.
In practice there are slight deviations from this standard which are given in the adjecent column.
It is not advisable to plug an appliance designed for 60 Hz into a 50 Hz wall outlet.
Make sure you carry electrical equipment (laptop, hairdryer, cellphone charger, etc.) that is designed for 110/230 Volts and 50/60 Hertz.

Mains
Albania - 220V 50Hz
Andorra - 220V 50Hz
Armenia - 220V 50Hz
Austria - 230V 50Hz
Azerbaijan - 220V 50Hz
Azores - 220V 50 Hz
Belarus - 220V 50Hz
Belgium - 230V 50Hz
Bosnia Herzegovina - 220V 50Hz
Bulgaria - 220V 50Hz
Croatia - 220V 50Hz
Czech Republic - 230V 50Hz
Denmark - 220V 50Hz
England - 240V 60Hz
Estonia - 220V 50Hz
Finland - 220V 50Hz
France - 220V 50Hz
Georgia - 220V 50Hz
Germany - 220V 50Hz
Greece - 220V 50Hz
Hungary - 220V 50Hz
Iceland - 220V 50Hz
Ireland - 220V 50Hz
Italy - 220V 50Hz
Latvia - 220V 50Hz
Liechtenstein - 220V 50Hz
Lithuania - 220V 50Hz
Luxembourg - 220V 50Hz
Macedonia - 220V 50Hz
Malta - 240V 50Hz
Moldova - 220V 50Hz
Netherlands - 220V 50Hz
Norway - 230V 50Hz
Poland - 220V 50Hz
Portugal - 220V 50Hz
Romania - 220V 50Hz
Russia - 220V 50Hz
Serbia - 220V 50Hz
Slovakia - 220V 50Hz
Slovenia - 220V 50Hz
Spain - 120/220V 50Hz
Sweden - 240V 50Hz
Switzerland - 110/220V 50Hz
Ukraine - 220V 50Hz