The power supply in Greece is 220 V AC at 50 Hz. You may require an adapter for the round two-pin sockets in use in Greece. Power cuts are not uncommon.
The definition for time zones can be written in short form as UTC±n (or GMT±n), where n is the offset in hours. Here is an example given the local time in Athens and New York City at 12:00pm UTC when daylight savings time is not in effect:
Athens Standard Time Zone: GMT/UTC + 2 hours = 2:00pm
NYC Standard Time Zone: GMT/UTC – 5 hours = 7:00am
Athens is on Eastern Europe Time and observes Daylight Savings time from the last Sunday in March to the last Sunday in October.