“And this day shall become a memorial for you, and you shall observe it as a festival for the L-RD, for your generations, as an eternal decree shall you observes it. For seven days you shall eat unleavened bread, but on the first day you shall remove the leaven from your homes ... you shall guard the unleavened bread, because on this very day I will take you out of the land of Egypt; you shall observe this day for your generations as an eternal decree”. - Exodus 12:14-17

"And thou shall tell thy son in that day, saying: it is because of that which the Lord did for me, when I came forth out of Egypt."

Pesach begins on the 15th day of the Jewish month of Nissan. It is the first of the three major festivals with both historical and agricultural significance (the other two are Shavuot and Sukkot). Agriculturally, it represents the beginning of the harvest season in Israel, but little attention is paid to this aspect of the holiday. The primary observances of Pesach are related to the Exodus from Egypt after generations of slavery.

This story is told in Exodus, Ch. 1-15. Many of the Pesach observances are instituted in Chs. 12-15. The name "Pesach" (PAY-sahch, with a "ch" as in the Scottish "loch") comes from the Hebrew root Pei-Samekh-Cheit, meaning to pass through, to pass over, to exempt or to spare. It refers to the fact that God "passed over" the houses of the Jews when he was slaying the firstborn of Egypt. In English, the holiday is known as Passover. "Pesach" is also the name of the sacrificial offering (a lamb) that was made in the Temple on this holiday.

The holiday is also referred to as Chag Ha-Aviv, (the Spring Festival), Chag ha-Matzot, (the Festival of Matzahs), and Z'man Cheiruteinu , (the Time of Our Freedom) (again, all with those Scottish "ch"s).

Together with Sukkot ("Tabernacles") and Shavuot ("Pentecost"), Passover is one of the three pilgrim festivals (Shloshet Ha'Regalim) during which the entire Jewish population made a pilgrimage to Jerusalem, at the time when the Temple in Jerusalem was standing.

In Israel, Passover is a 7-day holiday, with the first and last days celebrated as a full festival (involving abstention from work, special prayer services and holiday meals).

However, out of Israel it is traditionally celebrated for 8 days (although Reform Jews celebrate for 7 days), with the first two days and last two days celebrated as full festivals. The intervening days are known as Chol HaMoed ("festival weekdays").

The primary symbol of Passover is the matzah a flat” bread" as a reminder the hurriedly-baked bread that the Jews ate after their hasty departure from Egypt. According to Halakha, matzo may be made from flour derived from five types of grain: wheat, barley, spelt, oats and rye. The dough for matzo is made when flour is added to water only, which has not been allowed to rise for more than 18–22 minutes prior to baking.