Certain terms are used very commonly for groups of holidays.
- The Hebrew-language term Yom Tov (יום טוב), sometimes referred to as "festival day," usually refers to the six biblically-mandated festival dates on which all activities prohibited on Shabbat are prohibited, except for some related to food preparation. These include the first and seventh days of Passover, [first day of] Shavuot, both days of Rosh Hashanah, first day of Sukkot, and [first day of] Shemini Atzeret. By extension, outside the Land of Israel, the second-day holidays known under the rubric Yom tov sheni shel galuyot (literally, "Second Yom Tov of the Diaspora")—including Simchat Torah—are also included in this grouping. Colloquially, Yom Kippur, a biblically-mandated date on which even food preparation is prohibited, is often included in this grouping. The tradition of keeping two days of Yom Tov in the diaspora has existed since roughly 300 BCE.
- The English-language term High Holy Days (or High Holidays) refers to Rosh Hashanah and Yom Kippur collectively. Its Hebrew analogue, Yamim Nora'im (ימים נוראים), "Days of Awe”, is more flexible: it can refer just to those holidays, or to the Ten Days of Repentance, or to the entire penitential period, starting as early as the beginning of Elul, and (more rarely) ending as late as Shemini Atzeret.
- The term Three Pilgrimage Festivals (שלוש רגלים, shalosh regalim) refers to Passover, Shavuot and Sukkot. Within this grouping Sukkot normally includes Shemini Atzeret and Simchat Torah.
Terminology used to describe holidays
Certain terminology is used in referring to different categories of holidays, depending on their source and their nature:
Shabbat (שבת) (Ashkenazi pron. from Yiddish shabbos), or Sabbath, is referred to by that name exclusively. Similarly, Rosh Chodesh (ראש חודש) is referred to by that name exclusively.
- Yom tov (יום טוב) (Ashkenazi pron. from Yid. yontif) (lit., "good day"): See "Groupings" above.
- Moed (מועד) ("festive season"), plural moadim (מועדים), refers to any of the Three Pilgrimage Festivals of Passover, Shavuot and Sukkot. When used in comparison to Yom Tov, it refers to Chol HaMoed, the intermediate days of Passover and Sukkot.
- Ḥag or chag (חג) ("festival"), plural chagim (חגים), can be used whenever yom tov or moed is. It is also used to describe Hanukkah and Purim, as well as Yom Ha'atzmaut (Israeli Independence Day) and Yom Yerushalayim (Jerusalem Day).
- Ta'anit (תענית), or, less commonly, tzom (צום), refers to a fast. These terms are generally used to describe the rabbinic fasts, although tzom is used liturgically to refer to Yom Kippur as well.
"Work" on Sabbath and biblical holidays
The most notable common feature of Shabbat and the biblical festivals is the requirement to refrain from melacha on these days.[Note 2] Melacha is most commonly translated as "work"; perhaps a better translation is "creative-constructive work". Strictly speaking, Melacha is defined in Jewish law (halacha) by 39 categories of labor that were used in constructing the Tabernacle while the Jews wandered in the desert. As understood traditionally and in Orthodox Judaism:
- On Shabbat and Yom Kippur all melacha is prohibited.
- On a Yom Tov (other than Yom Kippur) which falls on a weekday, not Shabbat, most melacha is prohibited. Some melacha related to preparation of food is permitted.[Note 3][Note 4]
- On weekdays during Chol HaMoed, melacha is not prohibited per se. However, melacha should be limited to that required either to enhance the enjoyment of the remainder of the festival or to avoid great financial loss.
- On other days, there are no restrictions on melacha.[Note 5]
In principle, Conservative Judaism understands the requirement to refrain from melacha in the same way as Orthodox Judaism. In practice, Conservative rabbis frequently rule on prohibitions around melacha differently from Orthodox authorities. Still, there are a number of Conservative/Masorti communities around the world where Sabbath and Festival observance fairly closely resembles Orthodox observance.[Note 6]
However, many, if not most, lay members of Conservative congregations in North America do not consider themselves Sabbath-observant, even by Conservative standards. At the same time, adherents of Reform Judaism and Reconstructionist Judaism do not accept halacha, and therefore restrictions on melacha, as binding at all.[Note 7] Jews fitting any of these descriptions refrain from melacha in practice only as they personally see fit.
Shabbat and holiday work restrictions are always put aside in cases of pikuach nefesh, which is saving a human life. At the most fundamental level, if there is any possibility whatsoever that action must be taken to save a life, Shabbat restrictions are set aside immediately, and without reservation.[Note 8] Where the danger to life is present but less immediate, there is some preference to minimize violation of Shabbat work restrictions where possible. The laws in this area are complex.
Second day of biblical festivals
The Torah specifies a single date on the Jewish calendar for observance of holidays. Nevertheless, festivals of biblical origin other than Shabbat and Yom Kippur are observed for two days outside the land of Israel, and Rosh Hashanah is observed for two days even inside the land of Israel.
Dates for holidays on the Jewish calendar are expressed in the Torah as "day x of month y." Accordingly, the beginning of month y needs to be determined before the proper date of the holiday on day x can be fixed. Months in the Jewish calendar are lunar, and originally were proclaimed by the blowing of a shofar. Later, the Sanhedrin received testimony of witnesses saying they saw the new crescent moon.[Note 9] Then the Sanhedrin would inform Jewish communities away from its meeting place that it had proclaimed a new moon. The practice of observing a second festival day stemmed from delays in disseminating that information.
- Rosh Hashanah. Because of holiday restrictions on travel, messengers could not even leave the seat of the Sanhedrin until the holiday was over. Inherently, there was no possible way for anyone living away from the seat of the Sanhedrin to receive news of the proclamation of the new month until messengers arrived after the fact. Accordingly, the practice emerged that Rosh Hashanah was observed on both possible days, as calculated from the previous month's start, everywhere in the world.[Note 10]
- Three Pilgrimage Festivals. Sukkot and Passover fall on the 15th day of their respective months. This gave messengers two weeks to inform communities about the proclamation of the new month. Normally, they would reach most communities within the land of Israel within that time, but they might fail to reach communities farther away (such as those in Babylonia or overseas). Consequently, the practice developed that these holidays be observed for one day within Israel, but for two days (both possible days as calculated from the previous month's start) outside Israel. This practice is known as yom tov sheni shel galuyot, "second day of festivals in exile communities".
- For Shavuot, calculated as the fiftieth day from Passover, the above issue did not pertain directly, as the "correct" date for Passover would be known by then. Nevertheless, the Talmud applies the same rule to Shavuot, and to the Seventh Day of Passover and Shemini Atzeret, for consistency.
Yom Kippur is not observed for two days anywhere because of the difficulty of maintaining a fast over two days.[Note 11]
- Shabbat is not observed based on a calendar date, but simply at intervals of seven days. Accordingly, there is never a doubt of the date of Shabbat, and it need never be observed for two days.[Note 12]
Adherents of Reform Judaism and Reconstructionist Judaism generally do not observe the second day of festivals, although some do observe two days of Rosh Hashanah.