New Year’s Day, also simply called New Year or New Year’s, is observed on January 1, the first day of the year on the modern Gregorian calendar as well as the Julian calendar. In present day, with most countries now using the Gregorian calendar as their de facto calendar, New Year’s Day is probably the most celebrated public holiday, often observed with fireworks at the stroke of midnight as the new year starts in each time zone. Other global New Year’s Day traditions include making New Year’s resolutions and calling one’s friends and family.

Source: Wikipedia