The last week of Lent is called Holy Week, and it contains the days of the Easter Triduum, including Maundy Thursday (also known as Holy Thursday), commemorating the Last Supper and its preceding foot washing, as well as Good Friday, commemorating the crucifixion and death of Jesus. Easter is followed by a fifty-day period called Eastertide, or the Easter Season, ending with Pentecost Sunday.
Easter is a moveable feast, meaning it is not fixed in relation to the civil calendar. The First Council of Nicaea (325) established the date of Easter as the first Sunday after the full moon (the Paschal Full Moon) following the March equinox. Ecclesiastically, the equinox is reckoned to be on 21 March (although the astronomical equinox occurs on 20 March in most years), and the "Full Moon" is not necessarily on the astronomically correct date. The date of Easter therefore varies between 22 March and 25 April inclusive. Eastern Christianity bases its calculations on the Julian calendar, whose 21 March corresponds, during the 21st century, to 3 April in the Gregorian calendar, and in which therefore the celebration of Easter varies between 4 April and 8 May.
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 include sunrise services, exclaiming the Paschal greeting, clipping the church and decorating Easter eggs, a symbol of the empty tomb. 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.
Orthodox Easter date
Orthodox churches such as the Greek church, base their Easter date on the Julian calendar, while other Christians use the Gregorian calendar.
Modern Easter celebrations revolve around eggs. They may be painted, rolled down hills or eaten if they are of the chocolate variety. The Christian tradition of egg is aid to represent rebirth and resurrection - new life being born from the egg. It's also been said that egg recalls the shape of the stone that rolled away on Easter Sunday form the tomb that held Jesus' body.
This egg tradition is almost certainly a distillation of a much older pagan custom celebrating spring. The ancient Persians celebrated their new year at the time of the vernal equinox by painting eggs.
Its adoption into the Christian traditions would have been quite seamless, as eggs are banned during the period of Lent preceding Easter - in fact in many households the last eggs before Easter would have been used to make Pancakes on Pancake Tuesday.