What Is Passover?

white seder plate with lamb bone
A plate filled with traditional foods used during Passover. (Image credit: Getty/Tetra Images)

What is Passover?

Passover is one of the most important holidays in the Jewish calendar. It's an eight-day festival (seven days for Reform Jews and Jews in Israel) celebrated in the early spring, starting on the 15th day of the Hebrew month of Nisan. The 14th day of Nisan begins on the night of the first full moon after the vernal equinox.

On the Gregorian calendar, Nisan usually falls in March or April. This year, Passover will start on the evening of April 5, 2023.

What does Passover commemorate?

It commemorates the emancipation of the Israelites from slavery in ancient Egypt.

How were the Israelites emancipated?

Facsimile copy of a 15th century manuscript of the German School showing a depiction of Exodus 10:1-20: the plague of the locusts, one of the ten plagues of Egypt. (Image credit: Heritage Image Partnership Ltd via Alamy Stock Photo)

The story goes like this, according to the Old Testament: After generations of backbreaking labor and unbearable horrors at the hands of the Egyptian people, God saw the Israelites' distress. He sent Moses to Pharaoh with a message: "Send forth My people, so that they may serve Me" (Exodus 8:1). But despite numerous warnings, Pharaoh refused to heed God's command. God then sent upon Egypt ten devastating plagues, afflicting them and destroying everything from their livestock to their crops.

At the stroke of midnight of the 15th day of Nisan, God sent the last of the 10 plagues to the Egyptians, killing their firstborn. However, he spared the Children of Israel, "passing over" their homes hence the name of the holiday. Pharaoh's resistance was broken, and he virtually chased his former slaves out of the land. Led by Moses, an estimated 600,000 men, plus many more women and children, began the trek to Mount Sinai. Seven days later, the Red Sea parted and they left Egypt.

If the journey out of Egypt took seven days, why is the festival eight days long?

Orthodox Jews living outside Israel celebrate an extra day due to uncertainty as to which day is actually the start of the holiday. Traditionally, that decision was made at the Temple of Jerusalem, and the news had to travel far to reach people living far away. Reform Jews and Jews living in Israel do not celebrate the extra day.

What's unleavened bread?

Unleavened bread is made without yeast or sourdough culture. It is a simple, unfermented bread made with flour, water, and salt and then thoroughly rolled into flattened dough. During Passover, Jews eat cracker-like unleavened bread called matzah.

Why do Jews eat unleavened bread during Passover?

Unleavened bread called matzah is eaten during Passover. (Image credit: Roman Yanushevsky)

According to the Passover story, the Israelites left Egypt in such a hurry that the bread they baked as provisions for the way did not have time to rise. To commemorate the unleavened bread that the Israelites ate when they left Egypt, observant Jews don't eat or even retain in their possession any leavened grain (or chametz) from midday of the day before Passover until the conclusion of the holiday. They rid their homes of any food or drink that contains even a trace of wheat, barley, rye, oats, spelt or their derivatives, and which wasn't guarded from leavening or fermentation. This includes bread, cake, cookies, cereal, pasta and most alcoholic beverages. Moreover, almost any processed food or drink can be assumed to be chametz unless certified otherwise.

What is the search for chametz?

Traditionally, Jews do a formal search for remaining chametz after nightfall two evenings before Passover. A blessing is read, the lights are turned off, and, by candlelight, one or more members of the household proceed from room to room to check that no crumbs remain in any corner. This search, known as "bedikat chametz," is described in Pesachim, a tractate of Passover laws in the collection of Jewish oral traditions known as the Mishnah.

Bedikat chametz is typically conducting with a feather and a wooden spoon; the former, to dust crumbs out of their hiding places, and the latter, to collect the crumbs. Customarily, 10 morsels of bread no smaller than the size of an olive — a measure called a "kezayit" — are hidden throughout the house in order to ensure that some chametz will be found. The next morning, on the 14th of Nisan, any leavened products that remain in the householder's possession, along with the 10 morsels of bread from the previous night's search, are burned.

What is the Seder?

The highlight of Passover is the Seder, observed on each of the first two nights of the holiday. The Seder is a ritual-packed feast.

The focal points are eating matzah, as explained above, eating bitter herbs to commemorate the bitter slavery endured by the Israelites, drinking four cups of wine or grape juice to celebrate the freedom obtained by the Israelites at the time of the first Passover, and the recitation of the "Haggadah," a liturgy that describes in detail the story of the Exodus from Egypt. Jews have a Biblical obligation to recount to their children the story of the Exodus on the night of Passover.

What are the four questions?

During Seder, to spark discussion of the Exodus, the youngest child in the household is encouraged to ask, "Why is this night different from all other nights?" The storytelling begins, and at key moments the child asks these four questions:

On all other nights, we eat either unleavened or leavened bread, but tonight we eat only unleavened bread? On all other nights, we eat all kinds of vegetables, but tonight, we eat only bitter herbs? On all other nights, we do not dip [our food] even once, but tonight we dip twice? On all other nights, we eat either sitting or reclining, but tonight we only recline?

Thus prompted, the adults explain the celebration of Passover.

Can Jews work during Passover?

In Israel, Jews cease working for the duration of the festival. In most other places, Orthodox Jews celebrate the first two and last two days of the festival by ceasing all manual labor, but they may do work during the days in between. Reform Jews actively celebrate only the first and last days of their seven-day-long Passover.

Do Christians celebrate Passover?

Some Christians do celebrate a form of Passover, albeit with an abbreviated Seder that is tied to Easter and only loosely tied to the Old Testament Exodus. Christians focus on redemption from the bondage of sin through the sacrifice of Jesus Christ, rather than the Jewish Passover's celebration of redemption from bondage in the land of Egypt.

Christian Passover Seders are sometimes held on the evening corresponding to the 14th of Nisan rather than the 15th, since the former is taken to be the day Jesus was executed in Jerusalem.

Live Science senior writer Mindy Weisberger contributed reporting to this story.

Natalie Wolchover

Natalie Wolchover was a staff writer for Live Science from 2010 to 2012 and is currently a senior physics writer and editor for Quanta Magazine. She holds a bachelor's degree in physics from Tufts University and has studied physics at the University of California, Berkeley. Along with the staff of Quanta, Wolchover won the 2022 Pulitzer Prize for explanatory writing for her work on the building of the James Webb Space Telescope. Her work has also appeared in the The Best American Science and Nature Writing and The Best Writing on Mathematics, Nature, The New Yorker and Popular Science. She was the 2016 winner of the  Evert Clark/Seth Payne Award, an annual prize for young science journalists, as well as the winner of the 2017 Science Communication Award for the American Institute of Physics.