The Gregorian calendar - was introduced in 1582 by Pope Gregory XIII. It is currently used worldwide.

Gregorian calendar, the Julian calendar was preceded, which was introduced by the Romans seven hundred years after the founding of Rome. After revision in 45 BC. He began to pay in the capital of the empire and gradually spread in all countries of the Christian world. A major change occurred in 1582, when he was in a Catholic environment introduced Gregorian calendar. Culminated in dissatisfaction with the church leaders retarded important terms (eg vernal equinox), the epicenter of religious festivals and ceremonies. Julian year has in fact 365.25, but the so-called tropical year (the time from solstice to solstice) is 11 minutes shorter.

The Gregorian calendar almost fixated on March 21 as the day of the vernal equinox. The introduction of the Gregorian system was progressive in the world. In Europe, prevented him from states with the Orthodox and the Greek Catholic tradition, and later adopted him as a Protestant country. In Russia paid the Julian calendar until the end of the first world war, in Greece even until 1923. Religious festivals in these countries still continue to be governed by the old calendar Julian.