Easter and the holidays that are related to it are moveable feasts, in that they do not fall on a fixed date in the calendar year (which follows the motion of the Sun and the seasons). Instead, they are based on a lunar calendar like the Jews have been using. After the First Council of Nicaea in 325 it was decided that Easter would be celebrated on the Sunday on or after the first full moon after the day of the vernal equinox. Eventually, all churches accepted the Alexandrian method of computing Easter, which set the vernal equinox at 21 March (the actual equinox may fall one or two days earlier or later), and the date of the full moon was to be determined by using the Metonic cycle. A problem here is the difference between the western churches and the Eastern Orthodox Churches. The former now use the Gregorian Calendar to calculate the date of Easter, while the latter still use the original Julian Calendar. The World Council of Churches proposed a reform of the method of determining the date of Easter at a summit in Aleppo, Syria, in 1997. This reform would have eliminated the difference in the date between the Eastern and Western churches. The reform was due to be implemented starting in 2001, but it failed. See Reform of the date of Easter.
Easter marks the end of the forty-six days of the Lenten Season: a period of fasting and penitence in preparation for Easter, which begins on Ash Wednesday and ends on Easter. The Lenten Season really comprises 40 days since the 6 Sundays during this period are excluded from the Lenten fast, and are days that set apart to commemorate Easter Sunday.
The days before Easter also are special in the Christian tradition: the Sunday before is Palm Sunday, and the last three days before Easter are Maundy Thursday, Good Friday and Silent Saturday. Palm Sunday, Maundy Thursday and Good Friday respectively commemmorate Jesus's entry in Jerusalem, the Last Supper and the Crucifixion.
In the United States, the Easter holiday has been secularized, so that the main holiday event for many Americans is the coloring of Easter eggs, followed on Easter Sunday by an Easter egg hunt, in which young children gather the eggs that have been hidden in their homes or yards. According to the children's stories, eggs and other treats are delivered by the Easter Bunny in the form of an Easter basket which children find waiting for them when they wake up on Easter Sunday. The Easter Bunny's motives for doing this are seldom clarified. The association of a bunny with eggs may be due to the Egyptian symbol of fertility, the desert hare.
When is Easter? See