Easter[nb 1] (Old English Ēostre; Latin: Pascha; Greek Πάσχα Paskha, the latter two derived from Hebrew: פֶּסַח Pesaḥ) is a festival and holiday that was instituted to celebrate the resurrection of Jesus Christ on the third day after his crucifixion at Calvary as described in the New Testament. Easter is the culmination of the Passion of Christ, preceded by Lent, a forty-day period of fasting, prayer, and penance.
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 from 22 March to 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. There are also various traditional Easter foods that vary regionally.
Chapter 1. Etymology
The word Easter is held by some to have originally referred to the name of an Anglo-Saxon goddess, Ēostre.[nb 3] Easter is held by others to have originally referred to the name of a Babylonian goddess, Ishtar.  Others surmise that Eostre and Ishtar, pronounced identically, are two forms of the same word, referring to two forms of the same goddess, although the spelling differentiated through time and distance. 
In Greek and Latin, the Christian celebration was and is called Πάσχα, Pascha, words derived, through Aramaic, from the Hebrew term Pesach (פֶּסַח), known in English as Passover, which originally denoted the Jewish festival commemorating the story of the Exodus. Already in the 50s of the 1st century, Paul, writing from Ephesus to the Christians in Corinth, applied the term to Christ, and it is unlikely that the Ephesian and Corinthian Christians were the first to hear Exodus 12 interpreted as speaking about the death of Jesus, not just about the Jewish Passover ritual. In most of the non-English speaking world, the feast is known by names derived from Greek and Latin Pascha.[
The New Testament teaches that the resurrection of Jesus, which Easter celebrates, is a foundation of the Christian faith. The resurrection established Jesus as the powerful Son of God and is cited as proof that God will judge the world in righteousness. God has given Christians “a new birth into a living hope through the resurrection of Jesus Christ from the dead”. Christians, through faith in the working of God are spiritually resurrected with Jesus so that they may walk in a new way of life.
Easter is linked to the Passover and Exodus from Egypt recorded in the Old Testament through the Last Supper and crucifixion that preceded the resurrection. According to the New Testament, Jesus gave the Passover meal a new meaning, as he prepared himself and his disciples for his death in the upper room during the Last Supper. He identified the matzah and cup of wine as his body soon to be sacrificed and his blood soon to be shed. Paul states, “Get rid of the old yeast that you may be a new batch without yeast—as you really are. For Christ, our Passover lamb, has been sacrificed”; this refers to the Passover requirement to have no yeast in the house and to the allegory of Jesus as the Paschal lamb.
One interpretation of the Gospel of John is that Jesus, as the Passover lamb, was crucified at roughly the same time as the Passover lambs were being slain in the temple, on the afternoon of Nisan 14. The scriptural instructions specify that the lamb is to be slain “between the two evenings”, that is, at twilight. By the Roman period, however, the sacrifices were performed in the mid-afternoon. Josephus, Jewish War 6.10.1/423 (“They sacrifice from the ninth to the eleventh hour”). Philo, Special Laws 2.27/145 (“Many myriads of victims from noon till eventide are offered by the whole people”).
English: King James Version (1611) - KJV
14 And it was the preparation of the passover, and about the sixth hour: and he saith unto the Jews, Behold your King!
The first Christians, Jewish and Gentile, were certainly aware of the Hebrew calendar,[nb 4] and there is no direct evidence that they celebrated any specifically Christian annual festivals. It was probably as an aspect of Passover that Jewish Christians, the first to do so, celebrated the resurrection of Jesus, dated close to Passover.
Direct evidence for the Easter festival begins to appear in the mid-2nd century. Perhaps the earliest extant primary source referencing Easter is a mid-2nd-century Paschal homily attributed to Melito of Sardis, which characterizes the celebration as a well-established one. Evidence for another kind of annual Christian festival, the commemoration of martyrs, begins to appear at about the same time as evidence for the celebration of Easter.
While martyrs’ days (usually the individual dates of martyrdom) were celebrated on fixed dates in the local solar calendar, the date of Easter was fixed by means of the local Jewish lunisolar calendar. This is consistent with the celebration of Easter having entered Christianity during its earliest, Jewish period, but does not leave the question free of doubt.
The ecclesiastical historian Socrates Scholasticus attributes the observance of Easter by the church to the perpetuation of its custom, “just as many other customs have been established”, stating that neither Jesus nor his Apostles enjoined the keeping of this or any other festival. Although he describes the details of the Easter celebration as deriving from local custom, he insists the feast itself is universally observed.
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 (both of which follow the cycle of the sun and the seasons). Instead, the date for Easter is determined on a lunisolar calendar similar to the Hebrew 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 (even though the equinox occurs, astronomically speaking, on 20 March in most years), and the “full moon” is not necessarily the astronomically correct date.
In Western Christianity, using the Gregorian calendar, Easter always falls on a Sunday between 22 March and 25 April inclusive, within about seven days after the astronomical full moon. The following day, Easter Monday, is a legal holiday in many countries with predominantly Christian traditions.
Eastern Christianity bases its calculations on the Julian Calendar. Because of the 13-day difference between the calendars between 1900 and 2099, 21 March corresponds, during the 21st century, to 3 April in the Gregorian Calendar. Easter therefore varies between 4 April and 8 May on the Gregorian calendar (the Julian calendar is no longer used as the civil calendar of the countries where Eastern Christian traditions predominate). Also, because the Julian “full moon” is always several days after the astronomical full moon, the eastern Easter is often later, relative to the visible moon’s phases, than western Easter.
Among the Oriental Orthodox some churches have changed from the Julian to the Gregorian calendar and the date for Easter as for other fixed and moveable feasts is the same as in the Western church.
Section 1. Computations
In 725, Bede succinctly wrote, “The Sunday following the full Moon which falls on or after the equinox will give the lawful Easter.” However, this does not reflect the actual ecclesiastical rules precisely. One reason for this is that the full moon involved (called the Paschal full moon) is not an astronomical full moon, but the 14th day of a calendar lunar month. Another difference is that the astronomical equinox is a natural astronomical phenomenon, which can fall on 19, 20 or 21 March, while the ecclesiastical date is fixed by convention on 21 March.
In applying the ecclesiastical rules, Christian churches use 21 March as the starting point in determining the date of Easter, from which they find the next full moon, etc. The Eastern Orthodox and Oriental Orthodox Churches continue to use the Julian calendar. Their starting point in determining the date of Orthodox Easter is also 21 March, but according to the Julian reckoning, which currently corresponds to 3 April in the Gregorian calendar.
In addition, the lunar tables of the Julian calendar are four days (sometimes five days) behind those of the Gregorian calendar. The 14th day of the lunar month according to the Gregorian system is only the ninth or tenth day according to the Julian. The result of this combination of solar and lunar discrepancies is divergence in the date of Easter in most years (see table).
Easter is determined on the basis of lunisolar cycles. The lunar year consists of 30-day and 29-day lunar months, generally alternating, with an embolismic month added periodically to bring the lunar cycle into line with the solar cycle. In each solar year (1 January to 31 December inclusive), the lunar month beginning with an ecclesiastical new moon falling in the 29-day period from 8 March to 5 April inclusive is designated as the paschal lunar month for that year.
Easter is the third Sunday in the paschal lunar month, or, in other words, the Sunday after the paschal lunar month’s 14th day. The 14th of the paschal lunar month is designated by convention as the Paschal full moon, although the 14th of the lunar month may differ from the date of the astronomical full moon by up to two days. Since the ecclesiastical new moon falls on a date from 8 March to 5 April inclusive, the paschal full moon (the 14th of that lunar month) must fall on a date from 21 March to 18 April inclusive.
The Gregorian calculation of Easter was based on a method devised by the Calabrian doctor Aloysius Lilius (or Lilio) for adjusting the epacts of the moon, and has been adopted by almost all Western Christians and by Western countries which celebrate national holidays at Easter. For the British Empire and colonies, a determination of the date of Easter Sunday using Golden Numbers and Sunday letters was defined by the Calendar (New Style) Act 1750 with its Annexe. This was designed to exactly match the Gregorian calculation.