Passover begins at sundown on Monday, April 22

Passover, or "Pesach" in Hebrew, is celebrated by Jews around the world in commemoration of their liberation over 3,300 years ago by God from slavery in ancient Egypt, and their freedom as a people under the leadership of Moses as told in the Torah; Book of Exodus. 

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The remembrance lasts for up to eight days and it starts with Seder, a traditional 15-step meal which symbolizes the history of Passover.