Pope Gregory XIII (born Ugo Boncompagni in 1502) who introduced the “Gregorian” calendar in 1582. Until then, the Julian calendar had been in use since 45 BC.

The calendar many Christians follow is the Gregorian Calendar, introduced by Pope Gregory the 13th in 1582. The Julian Calendar, on the other hand, found its roots over 1500 years prior ...

Cultures throughout history have come up with their own unique ways to track the days, months, and seasons.

In 1582, Pope Gregory XIII introduced the Gregorian calendar. Prior to this, most of the Roman world and Europe had used the Julian calendar, introduced by Julius Caesar in 45 BCE.

Since at least the neolithic, humans have been creating calendars to keep track of the changing seasons. Secularly today, we used the Gregorian calendar introduced in 1582 by Pope Gregory XIII ...

To remedy this, Pope Gregory XIII introduced the Gregorian calendar in 1582, which is the same as the Julian calendar but with the exclusion of leap years for most centenary years (as outlined above).