What time is it in Europe?
Time zones in Europe and dealing with the 24-hour clock
Most of Western Europe is six hours ahead of Eastern Standard Time (or one hour ahead of GMT, Greenwich Mean Time). That means when it's 1pm in New York and 10am in San Francisco, it's 7pm in Paris.
Greece, much of Eastern Europe (Turkey, Romania, Bulgaria) and Finland are all seven hours ahead.
The British Isles (including Ireland), Portugal, and Iceland are all five hours ahead of EST (one hour behind the rest of Western Europe) and are all on GMT (Greenwich Mean Time).
Greenwich, England—formerly a village which is now part of Greater London—is the world's official arbiter of what time it is, set by an atomic clock (you can take the Tube there—Jubilee line—and set your watch by the big digital display, which is placed right over a funny line drawn down the middle of the planet officially separating the East and West hemispheres. Also, the Cutty Sark is moored at the riverside and there are some bloody good pubs, including one hanging over the Thames).
What Time Is It? 16:30 (Huh?)
Most Europeans use the 24-hour clock—known to us Yanks as "military time," though you'll never hear an Italian bark out a phrase like "at oh-six-hundred hours," not even in Italian (and not just because few Italians are silly enough to be awake at that ungodly hour).
They just refer to the morning hours like we do—9:00, 10:00, 11:43, etc. At noon they write 12:00, and when it gets to be 1pm they write 13:00, and then go take a nap (you gotta love riposo/siesta). Dinner may take place any time from 17:00 (Britain's 5pm repast) to 22:30 (Spain's 10:30pm feast).
The day ends at 24:00 (that's midnight), after which there's a wee hour when the minutes tick off 0:01, 0:02, 0:03...
When speaking, however, Europeans might use either the 24-hour-clock number, or a 12-hour-clock number followed by the phrase (in local lingo) "in the afternoon"—so at 3pm, they may say "it's fifteen o'clock" (or, more usually, just "it's fifteen") or they might say "it's three in the afternoon."
Just remember: If the hour is greater that 12, subtract 12 and add a "pm" in your head. That way, 20:00 becomes 8pm (time for dinner in Italy).