There are broadly three categories of Jewish holiday: biblical (Torah) holidays, those mentioned in the Torah (sometimes called the Jewish Bible); historic holidays or rabbinical holidays, those that are not mentioned in the Torah but instead are in the other later books of the Bible and have been decreed as holidays by the rabbis; and later holidays, those rooted in the twentieth century which are also based on history.
The holiday dates follow the Jewish calendar, which is based on both the solar and the lunar year. The structure of the calendar was formulated by Hillel the Second approximately 330-365 CE. Because many Jewish holidays have more than one significance, and are often connected to farming and harvest time, it was necessary to adjust the calendar so that holidays were celebrated in the right season. If the calendar were not adjusted to account for the fact that the lunar year is 10–11 days shorter than the solar year, then eventually the calendar would get out of sync and harvest time would have to be celebrated at the time of planting. To avoid this, Judaism adds a leap month to its calendar every two or three years to keep it in step with the solar year. The Jewish calendar standardizes the length of months and the addition of months over the course of a 19 year cycle, so that the lunar calendar realigns with the solar years. This explains why Jewish holidays move around in relation to the Western calendar. The Jewish day begins at sunset, which is why the Sabbath, for instance, is marked from Friday evening to Saturday evening.
Jewish holidays are celebrated in two ways: with a service of worship, and at home with the family. In general the one can say that the Jewish Holidays are been celebrated with the family and one’s own community. Torah was given to mankind as blueprint for a just society. The individual is important but the ultimate benefit can be reached only in the framework of a community or society as a whole. Daily prayer is a mitzvah or religious command for Jewish people. Jewish services of worship became more common in Judaism during the Babylonian captivity that followed the destruction of the First Temple some 2,500 years ago. The religious laws of the halakha allow sacrifice to God only in the Temple. To replace sacrifice, a culture of holding a service of worship evolved (i.e. prayers and not animal sacrifice), a culture that thrived even after the Israelites returned to Judea.
On weekdays, in Judaism, three services of daily worship are held and during festivals there are often four (Yom Kipur, The Day of Atonement, has five). It is generally agreed that community prayer is more significant than private prayer. The weekday prayers of Judaism are the evening prayer of maariv, the morning service of shacharit and the afternoon service or mincha. There is an additional prayer or service on the Sabbath and other holidays, called musaf.
For religious services in the home, the family first states why the holiday is being marked (kiddush, sanctifying the day with a cup of wine), then they celebrate it together. This is often done at mealtimes, although the meal simply provides the setting (Sometimes the meal is in itself also the mitzvah, commandment). As they have been throughout history, togetherness and community are important in modern Judaism. A festive meal, seuda, takes two to three hours and begins with the blessing of wine and bread. Orthodox Jews, among whom the Jews in Finland are numbered, say these blessings in Hebrew, as they do all prayers. The blessing of the wine and the bread is followed by special blessings related to the holiday being celebrated (this is the kiddush that was mentioned above). The foods served at a seuda vary in different parts of the world. In Finland, the foods are traditionally of Eastern European origin.
Shabbat – the Sabbath (weekly day of rest)
Rosh Hashanah – Jewish New Year (1st day of Tishrei)
Yom Kippur – Day of Atonement (10th day of Tishrei)
Sukkot, Feast of the Booths, or of the Tabernacles (15th day of Tishrei)
Simchat Torah, Rejoicing of the Torah (24th day of Tishrei)
Hanukkah – Festival of Lights or Feast of Dedication (25th day of Kislev)
Tu Bishvat – New Year of the Trees (15th day of Shvat)
Purim – Feast of Lots (14th day of Adar)
Pesach – Passover (15th day of Nisan)
Yom HaShoah – Holocaust Remembrance Day (27th day of Nisan)
Yom Hazikaron – a day of commemoration for soldiers and civilians killed in Israel’s wars (4th day of Ijar)
Yom Ha’atsmaut, Israel Independence Day (5th day of Iyar)
Lag BaOmer –33rd day of the Counting of the Omer period (18th day of Iyar)
Yom Yerushalayim – Jerusalem Day (28th day
Shavuot – Feast of Weeks or the giving of the Torah (6th day of Sivan)
Tisha B’Av – Day of Mourning of the Destruction
of the Temples (9th day of Av)