One of the holiest festivals of Christians, Easter commemorates the Resurrection of Jesus after his Crucifixion. Like the origin of the festival, the precise date of Easter Sunday too has been a matter of contention. Easter and the holidays that are related to it are moveable feasts, in that they do not fall on a fixed date in the Gregorian or Julian calendars (which follow the motion of the sun and the seasons). Instead, they are based on a lunar calendar. Early Christians celebrated Easter on different days of the week.
Talking about history, in 325 AD, the Council of Nicaea convoked by Emperor Constantine issued the Easter Rule, which stated that Easter shall be celebrated on the first Sunday that occurs after the first full moon on or after the vernal equinox. However, the "full moon" in the rule is the ecclesiastical full moon and it does not always occur on the same date as the astronomical full moon. The ecclesiastical "vernal equinox" is always on March 21. Therefore, Easter can be celebrated as early as on March 22 or as late as on April 25.
Another distinctive change that came about was with the celebration days. While traditionally, Eastertide lasted for forty days from Easter Day i.e. until Ascension Day, things are different in the present times. Nowadays, Easter officially lasts for the fifty days until Pentecost. In Western Christianity, Easter is always celebrated on the Sunday immediately following the Paschal Full Moon. A spring time festival, Easter, in Christian countries, is a religious holiday, celebrated with great pomp and show. Though primarily it commemorates the resurrection of Jesus Christ, the son of God, there are various customs and legends that are associated with it.
Easter also characterizes the end of Lent season, a period for fasting, prayer and penance. Celebration for Easter starts from days in advance. The last week of Lent observes Palm Sunday, which signifies Lord Jesus' successful entry to Jerusalem. On this day, the crowd at Jerusalem laid palm leaves at His feet, thereby acquiring the name as Palm Sunday. Holy Thursday or Maundy Thursday refers to the Last Supper, which was held in the evening, before the Crucifixion. Good Friday commemorates the anniversary of the Crucifixion, the day when Christ was crucified and died on the cross.
Easter Calendar 2021:
1st April - Western Calendar
8th April - Eastern Orthodox Church