Today marks the celebration of Easter in Orthodox Christianity.
Eastern Christianity bases its calculations for the date for Easter on the Julian calendar in which the celebration of Easter falls between 4 April and 8 May annually. In Eastern Christianity, every other religious festival in their calendar, including Christmas, is considered to be secondary in importance to the celebration of the Easter.
In Eastern Christianity, the spiritual preparation for Easter begins with Great Lent, which starts on Clean Monday and lasts for 40 continuous days (including Sundays). The last week of Great Lent (following the fifth Sunday of Great Lent) is called Palm Week, and ends with the day before which is called Lazarus Saturday. The Vespers which begins Lazarus Saturday officially brings Great Lent to a close, although the fast continues through the following week. After Lazarus Saturday comes Palm Sunday, Holy Week, and finally Easter itself, and the fast is broken immediately after the Paschal Divine Liturgy.
The Paschal Vigil begins with the Midnight Office, which is the last service of the Lenten Triodion and is timed so that it ends a little before midnight on Holy Saturday night. At the stroke of midnight the celebration itself begins, guaranteeing that no Divine Liturgy will come earlier in the morning, ensuring its place as the pre-eminent “Feast of Feasts” in the liturgical year.