New Years Day is observed on January 1. That is considered the first day of the year according to the Gregorian calendar. Romans originally dedicated New Years Day to “Janus”, the god of gates, doors and beginnings for whom the first month of the year is named. Janus = January. In present day, most countries use the Gregorian calendar as their calendar. New Years Day is probably the world’s most celebrated public holiday, often observed with fireworks at the stroke of midnight as the new year starts in each time zone.