Jewish holidays, also known as Jewish festivals or Yamim Tovim (Hebrew: יָמִים טוֹבִים, romanized: yāmīm ṭōvīm, lit. 'Good Days', or singular Hebrew: יוֹם טוֹב Yom Tov, in transliterated Hebrew []), are holidays observed by Jews throughout the Hebrew calendar. They include religious, cultural and national elements, derived from four sources: mitzvot ("biblical commandments"), rabbinic mandates, the history of Judaism, and the State of Israel.
Jewish holidays occur on the same dates every year in the Hebrew calendar, but the dates vary in the Gregorian. This is because the Hebrew calendar is a lunisolar calendar (based on the cycles of both the sun and moon), whereas the Gregorian is a solar calendar. Each holiday can only occur on certain days of the week, four for most, but five for holidays in Tevet and Shevat and six for Hanukkah (see Days of week on Hebrew calendar).
