The week before Easter is called Holy Week, and it contains the days of the Easter Triduum, including Maundy Thursday, commemorating the Maundy and Last Supper, as well as Good Friday, commemorating the crucifixion and death of Jesus. In western Christianity, Eastertide, the Easter Season, begins on Easter Sunday and lasts seven weeks, ending with the coming of the fiftieth day, Pentecost Sunday. In Orthodoxy, the season of Pascha begins on Pascha and ends with the coming of the fortieth day, the Feast of the Ascension.
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 Juliancalendars which follow only the cycle of the sun; rather, its date is determined on a lunisolar calendar similar to the Hebrew calendar. The First Council of Nicaea (325) established two rules, independence of the Jewish calendar and worldwide uniformity, which were the only rules for Easter explicitly laid down by the council. No details for the computation were specified; these were worked out in practice, a process that took centuries and generated a number of controversies. It has come to be the first Sunday after the full moon that occurs on or soonest after 21 March, but calculations vary in East and West. Details of this complicated computation are found below in the section Date.
Easter is linked to the Jewish Passover by much of its symbolism, as well as by its position in the calendar. In many languages, the words for “Easter” and “Passover” are identical or very similar. Easter customs vary across the Christian world, and includesunrise services, exclaiming the Paschal greeting, clipping the church, and decorating Easter eggs, a symbol of the empty tomb. The Easter lily, a symbol of the resurrection, traditionally decorates the chancel area of churches on this day and for the rest of Eastertide. Additional customs that have become associated with Easter and are observed by both Christians and some non-Christians include egg hunting, the Easter Bunny, and Easter parades. There are also various traditionalEaster foods that vary regionally.