However, most branches of the Eastern Orthodox Church still use the Julian calendar for calculating the date of Easter, upon which the timing of all the other moveable feasts depends.
Some Orthodox churches have adopted the Revised Julian calendar for the observance of fixed feasts, while other Orthodox churches retain the Julian calendar for all purposes. In the form of the Alexandrian calendar, it is the basis for the Ethiopian calendar, which is the civil calendar of Ethiopia. suffix (denoting Old Style, Julian or New Style, Gregorian).
They usually occurred every second or third year, but were sometimes omitted for much longer, and occasionally occurred in two consecutive years.
The Julian calendar has a regular year of 365 days divided into 12 months, as listed in the table below. The Julian year is, therefore, on average 365.25 days long.
It was intended to approximate the tropical (solar) year.
According to the later writers Censorinus and Macrobius, the ideal intercalary cycle consisted of ordinary years of 355 days alternating with intercalary years, alternately 377 and 378 days long.
In this system, the average Roman year would have had days over four years, giving it an average drift of one day per year relative to any solstice or equinox.
Greece made the change for civil purposes on 16 February/1 March 1923, but the national day (25 March), which was a religious holiday, was to remain on the old calendar.