Passover is an Independence Day celebration for Israelites, commemorating the Exodus from Egypt. Passover begins just before the evening, before Shabbat usually starts, and continues until dawn. It’s the only Holy Day that doesn’t last the full 24 hours. The dawn and the rest of the week is the Feast of Unleavened Bread. This day is observed as a Sabbath day, no work or anything secular is to be done this day. Reference: Exodus 12, 13 & Leviticus 23