Bits and Beyond...

GREGORIAN CALENDAR

The Gregorian Calendar was introduced in 1582, when Pope Gregory XIII modified the Julian calendar.  The purpose of this modification is to restore the date of Easter to spring.  Unlike the Julian Calendar, the years divisible by 100 in the Gregorian Calendar are not leap years, unless they are divisible by 400.  Thus, the years 1700, 1800 and 1900 were not leap years, while the years 1600 and 2000 were.