The Hebrew calendar is a lunar-based calendar, meaning a day begins and ends at sundown. Thus, all holidays begin at sundown of the day preceding the date shown and end at sundown of the (last) day shown.

Since the Hebrew calendar begins with Rosh Hashanah, the Jewish year always straddles two years from the gregorian calendar. In other words, spring holidays (such as Pesach and Shavuot) occur in the civil year following Rosh Hashanah. For example: Rosh Hashanah in the Hebrew year 5758 occurs on September 21-22, 1997 and Passover in the same Hebrew year occurs on April 1-2,1998.

An additional note: Since the calendar was created in Israel and there is a great time zone difference between Israel and America, American Jews observe some holidays for two days, while Israeli Jews observe only one day, to ensure that American Jews celebrate the holiday during the entire time that the holiday is observed in Israel.