According to Biblical command, Passover is to be observed for 7 days, beginning on Nissan 15, with the first and seventh days being observed as yom tov, when work is not performed. Since ancient times, rabbinic tradition mandates that the holidays be celebrated for an extra day in the Diaspora. As such, around the world Passover is an eight-day affair, with the first two and final two days celebrated as yom tov. In Israel, however, the holiday is observed for 7 days, as outlined in the Bible.

The Seder (Passover feast) is celebrated on the evening preceding Nissan 15, just after the onset of the holiday (Jewish days begin at night). In the Diaspora, it is observed again the following night.

It is forbidden to own or consume chametz (grain that has risen, including bread, pasta, whiskey etc.) for the entire 7- or 8-day holiday.

See the Passover calendar here.