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Passover, also called Pasch () or Pesach (; Biblical Hebrew: חַג הַפֶּסַח, romanized: Ḥag Ha‑Pesaḥ, lit. 'Pilgrimage of the Passing Over'), or Peysekh in Yiddish, is a major Jewish holiday and one of the Three Pilgrimage Festivals. It celebrates the Exodus of the Israelites from slavery in Egypt.
According to the Book of Exodus, God commanded Moses to tell the Israelites to slaughter a lamb and mark their doorframes with its blood, in addition to instructions for consuming the lamb that night. For that night, God would bring about the tenth plague, in which God would smite all the firstborn in Egypt. But when God saw the blood on the Israelites' doorframes, God would pass over their homes so that the plague should not enter (hence the name). The story is part of the broader Exodus narrative, in which the Israelites, while living in Egypt, are enslaved en masse by the Pharaoh to suppress them; when Pharaoh refuses God's demand to let them go, God sends ten plagues upon Egypt. After the tenth plague, Pharaoh permits the Israelites to leave. Scholars widely believe that the origins of Passover predate the biblical Exodus, with theories suggesting it evolved from earlier semi-nomadic or pre-Israelite rituals and was later transformed through religious and cultic traditions.
This story is recounted at the Passover Seder by reading the Magid section of the Haggadah. The Haggadah is a standardized ritual book for the Passover Seder, containing an account of the Exodus story, in fulfillment of the command "And thou shalt tell (וְהִגַּדְתָּ֣, higgad'ta) thy son in that day, saying: It is because of that which the LORD did for me when I came forth out of Egypt." Jews are forbidden from possessing or eating leavened foods (chametz) during the holiday.
Pesach starts on the 15th day of the Hebrew month of Nisan, which is considered the first month of the Hebrew year. The Jewish calendar is adjusted to align with the solar calendar so that 15 Nisan always falls on Sunday, Tuesday, Thursday, or Saturday. The Hebrew day starts and ends at sunset, so the holiday starts at sunset the day before. For example, in 2027, 15 Nisan will coincide with Thursday, April 22. Therefore, Pesach will start at sundown on Wednesday, April 21, 2027.

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