Why is Passover celebrated 7 days in Israel and 8 days outside of Israel?
The first day of Passover (first two in the diaspora) is considered a holy day (Yom Tov). On the first day the Jews left Egypt. The seventh day (and the 8th day in the diaspora) is also considered a holy day. On the seventh day the miracle of splitting the sea occurred. The days in between are the intermediate days of the festival.
