January 1 is the first day of the year in the Gregorian Calendar. There are 364 days remaining until the end of the year (365 in leap years). This date is slightly more likely to fall on a Friday, Sunday, or Tuesday (58 in 400 years each) than on Wednesday or Thursday (57), and slightly less likely to occur on a Saturday or Monday (56). This day is known as New Year's Day since the day marks the beginning of the year.

During the Middle Ages under the influence of the Catholic Church, many countries in western Europe moved the start of the year to one of several important Christian festivals – December 25 (the Nativity of Jesus), March 1, March 25 (the Annunciation), or even Easter. Eastern European countries (most of them with populations showing allegiance to the Orthodox Church) began their numbered year on September 1 from about 988.