The history of calendars goes back thousands of years. The oldest calendar is a Lunar Calendar found in Aberdeenshire, Scotland, from 8,000 BC.
The modern day calendar is known as the Gregorian calendar. This calendar is a refinement made in 1582 to the Julian calendar to help Easter align with the time of the year in which the First Council of Nicaea occurred.
“The Gregorian calendar is a solar calendar. A regular Gregorian year consists of 365 days and in a leap year, an intercalary or leap day is added as 29 February making the year 366 days. Normally a leap year occurs every 4 years, but the Gregorian calendar omits 3 leap days every 400 years, unlike the Julian calendar, which retains those leap days.”
The Gregorian calender is one of the most universal standards in the world making New Year’s Day the world’s most celebrated public holiday.