Jewish holidays, also known as Jewish festivals or Yamim Tovim (ימים טובים, "Good Days", or singular יום טוב Yom Tov, in transliterated Hebrew [English: /ˈjɔːm ˈtɔːv, joʊm ˈtoʊv/]), are holidays observed in Judaism and by Jews throughout the Hebrew calendar and include religious, cultural and national elements, derived from three sources: Biblical mitzvot ("commandments"); rabbinic mandates; Jewish history and the history of 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 (i.e., based on the cycles of both the sun and moon), whereas the Gregorian is a solar calendar.
Certain terms are used very commonly for groups of holidays.
Certain terminology is used in referring to different categories of holidays, depending on their source and their nature: