Gregorian Calendar

From Conservapedia

The Gregorian Calendar, named after Pope Gregory XIII, is the calendar that most use today (it is the most widely used in the world). It consists of 365 days in each year, with a 366-day leap year every fourth year.

It is the same as the Julian Calendar, except that years at the end of centuries (e.g. 1900) are not leap years unless they are divisible by 400.