Byzantine time
Byzantine time is a method of keeping time that originated in the Byzantine Empire.
It is now rarely used save for in Eastern Orthodox monasteries, for example, on Mount Athos in Greece and Mar Saba monastery in the West Bank. Ethiopia also uses this type of timing.
In Byzantine time, hour 0:00:00 begins daily at sunset rather than midnight. Due to seasonal variations in the length of a day, hour zero can vary by several hours throughout the year. The Byzantine calendar is a related method of keeping dates.