Happy new year/New Year's Day, also called simply New Year's or New Year, is observed on January 1, the first day of the year on the modern Gregorian calendar as well as the Julian calendar. In pre-Christian Rome under the Julian calendar, the day was dedicated to Janus, god of gateways and beginnings, for whom January is also named. As a date in the Gregorian calendar of Christendom, New Year's Day liturgically marked the Feast of the Naming and Circumcision of Jesus, which is still observed as such in the Anglican Church and Lutheran Church.[2][3] 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 Years' Day traditions include making New Year's resolutions and calling one's friends and family
Mesopotamia (Iraq) instituted the concept of celebrating the new year in 2000 BC, celebrated new year around the time of the vernal equinox, in mid-March.[4][5] The early Roman calendar designated March 1 as the new year. The calendar had just ten months, beginning with March. That the new year once began with the month of March is still reflected in some of the names of the months. September through December, our ninth through twelfth months, were originally positioned as the seventh through tenth months (septem is Latin for "seven," octo is "eight," novem is "nine," and decem is "ten.")

The first time the new year was celebrated on January 1 was in Rome in 153 BC (In fact, the month of January did not even exist until around 700 BC, when the second king of Rome, Numa Pontilius, added the months of January and February.) The new year was moved from March to January because that was the beginning of the civil year, the month that the two newly elected Roman consuls - the highest officials in the Roman republic - began their one-year tenure. But this new year date was not always strictly and widely observed, and the new year was still sometimes celebrated on March 1.