Kitniyot (Hebrew: קִטְנִיּוֹת, qitniyyot; literally "small things") refers to legumes, rice, maize, and other foods that are similar to grains. Ashkenazi Jews historically refrain from eating kitniyot on Passover, despite there not being a clear commandment to include them in the category of chametz. Since the 19th century, the Reform movement has permitted eating kitniyot, and in 2015 the Conservative movement followed suit. Sephardi Jews have always permitted eating kitniyot on Passover.
The Passover begins on the 15th day of the month of Nisan, which at present falls between March 26 and April 25 of the Gregorian calendar. The 15th day begins in the evening, after the 14th day, and the seder meal is eaten that evening. Passover is a spring festival, so the 15th day of Nisan typically begins on the night of a full moon after the northern vernal equinox. However, due to leap months falling after the vernal equinox, Passover sometimes starts on the second full moon after vernal equinox, as in 2016.
Pesach starts on the 15th day of the Hebrew month of Nisan, which is considered the first month of the Hebrew year. The Rabbinical Jewish calendar is adjusted to align with the solar calendar in such a way that 15 Nisan always coincides with Sunday, Tuesday, Thursday, or Saturday. The Hebrew day starts and ends at sunset, so the holiday starts at sunset the day before. For example, in 2024, 15 Nisan coincides with Tuesday, April 23. Therefore, Pesach starts at sundown on Monday, April 22.
The Samaritans use a calendrical system that uses a different method from that current in Rabbinic practice; it sometimes is the same date on the solar calendar, sometimes two days later, and sometimes an entire month later. In 2024, Rabbinical Passover begins at sunset on 22 April. On the calendar used by the Samaritans, 22 April 2024 is also the day of the Passover sacrifice. Karaite and Samaritan Passovers are each one day long followed by the six-day Festival of Unleavened Bread, for a total of seven days.