Fast of the Firstborn (Hebrew: תענית בכורות‎, Ta'anit B'khorot^[1] or תענית בכורים, Ta'anit B'khorim^[2]); is a unique fast day in Judaism which usually falls on the day before Passover (i.e. the fourteenth day of Nisan, a month in the Jewish calendar. Passover always begins on the fifteenth of the Hebrew month). Usually, the fast is broken at a siyum celebration (typically made at the conclusion of the morning services), which, according to prevailing custom, creates an atmosphere of rejoicing that overrides the requirement to continue the fast (see Breaking the fast below). Unlike most Jewish fast days, only firstborns are required to fast on the Fast of the Firstborn.

This fast commemorates the salvation of the Israelite firstborns during the Plague of the Firstborn (according to the Book of Exodus, the tenth of the ten plagues wrought upon Ancient Egypt prior to the Exodus of the Children of Israel), when, according to Exodus (12:29): "...God struck every firstborn in the Land of Mitzrayim (Ancient Egypt)...."^[3]

April 6 (Western)

Good Friday (from the senses pious, holy of the word "good"),^[1] is a religious holiday observed primarily by Christians commemorating the crucifixion of Jesus Christ and his death at Calvary. The holiday is observed during Holy Week as part of the Paschal Triduum on the Friday preceding Easter Sunday, and may coincide with the Jewish observance of Passover. It is also known as Holy Friday, Great Friday, Black Friday,^[2] or Easter Friday,^[3] though the latter properly refers to the Friday in Easter week.

Great Lent, or the Great Fast, is the most important fasting season in the church year in Eastern Christianity, which prepares Christians for the greatest feast of the church year, Pascha (Easter). In many ways Great Lent is similar to Lent in Western Christianity. There are some differences in the timing of Lent (besides calculating the date of Easter) and how it is practiced, both liturgically in the public worship of the church and individually.

One difference between Eastern Christianity and Western Christianity is the calculation of the date of Easter (see Computus). Most years, the Eastern Pascha falls after the Western Easter, and it may be as much as five weeks later; occasionally, the two dates coincide. Like Western Lent, Great Lent itself lasts for forty days, but unlike the West, Sundays are included in the count. Great Lent officially begins on Clean Monday, seven weeks before Pascha (Ash Wednesday is not observed in Eastern Christianity) and runs for 40 contiguous days, concluding with the Presanctified Liturgy on Friday of the Sixth Week. The next day is called Lazarus Saturday, the day before Palm Sunday. However, fasting continues throughout the following week, known as Passion Week or Holy Week, and does not end until after the Paschal Vigil early in the morning of Pascha (Easter Sunday).

Lent (Latin: Quadragesima, "fortieth"^[1]) is an observance in the liturgical year of many Christian denominations, lasting for a period of approximately six weeks leading up to Easter. In most Western denominations Lent is taken to run from Ash Wednesday to Maundy Thursday (Holy Thursday) or to Easter Eve.

The traditional purpose of Lent is the preparation of the believer—through prayer, penance, repentance, almsgiving, and self-denial. Its institutional purpose is heightened in the annual commemoration of Holy Week, marking the death and resurrection of Jesus, which recalls the events of the Passion of Christ on Good Friday, which then culminates in the celebration on Easter Sunday of the resurrection of Jesus Christ.

Holy Week (Latin: Hebdomas Sancta or Hebdomas Maior, "Greater Week"; Greek: Ἁγία καὶ Μεγάλη Ἑβδομάς, Hagia kai Megale Hebdomas) in Christianity is the last week of Lent and the week before Easter. It includes the religious holidays of Palm Sunday, Maundy Thursday (Holy Thursday), Good Friday, and Holy Saturday. It does not include Easter Sunday. In Eastern Orthodox tradition, Holy Week starts on Lazarus Saturday, the day before Palm Sunday. (Easter Sunday, for context, is the first day of the new season of the Great Fifty Days, or Eastertide, there being fifty days from Easter Sunday to Pentecost Sunday.)

Holy Week in the Christian year is the week immediately before Easter. The earliest Catholic allusion to the custom of marking this week as a whole with special observances is to be found in the Apostolical Constitutions (v. 18, 19), dating from the latter half of the 3rd century and 4th century. In this text, abstinence from flesh is commanded for all the days, while for the Friday and Sunday an absolute fast is commanded. Dionysius Alexandrinus in his canonical epistle (AD 260), refers to the 91 fasting days implying that the observance of them had already become an established usage in his time.^[1]

Celebrates the Exodus, the freedom from slavery of the Children of Israel from ancient Egypt that followed the Ten Plagues.

Passover (Hebrew, Yiddish: פֶּסַח Pesach, Tiberian: [pɛsaħ] ( listen), Modern Hebrew: /ˈpesaχ/ Pesah, Pesakh, Yiddish: Peysekh, Paysakh, Paysokh) is a Jewish holiday and festival. It commemorates the story of the Exodus, in which the ancient Israelites were freed from slavery in Egypt. Passover begins on the 15th day of the month of Nisan in the Jewish calendar, which is in spring in the Northern Hemisphere, and is celebrated for seven or eight days. It is one of the most widely observed Jewish holidays.