In the Gregorian calendar, New Year's Eve, also known as Old Year's Day or Saint Sylvester's Day in many countries, is the evening or the entire day of the last day of the year, 31 December. The last day of the year is commonly referred to as “New Year's Eve”. In many countries, New Year's Eve is celebrated with dancing, eating, drinking, and watching or lighting fireworks. Some Christians attend a watchnight service. The celebrations generally go on past midnight into New Year's Day, 1 January.