This is done every 2-3 years to keep the Jewish (lunar) months in line with the solar seasons.
The Jewish calender has on averge 352 days per year because its months are between 29 and 30 days long (as opposed to Gregorian months which are typically between 30 and 31 days long). Therefore, if the Jewish calendar did not make any adjustments, Hebrew years would be entirely out of sync with the solar year. As a result, leap years are added 7 times in the course of a 19 year cycle to balance out the 352 day-years with 382 day-years often enough to reach the same number of days having passed.
Jewish people.
The Jews follow a lunar calendar to which is added a leap month often enough to keep it in step with the solar year.
The Jewish calendar is a lunisolar calendar. Therefore the Jewish day begins at sundown, and the months keep in step with the phases of the moon. The problem with strictly lunar calendars is that there are approximately 12.4 lunar months in every solar year, so a 12-month lunar calendar is about 11 days shorter than a solar year and a 13-month lunar is about 19 days longer than a solar year. To compensate for this drift, the Jewish calendar uses a 12-month lunar calendar with an extra month occasionally added. The months are: Nissan, Iyar, Sivan, Tamuz, Av, Elul, Tishrei, Cheshvan, Kislev, Tevet, Shevat, Adar I (leap years only), Adar. The Jewish new year is celebrated in Tishrei, which occures in early Autmn. The current year is 5774, which counts up from the time of the creation of the world, 5,774 years ago.
Purim is the Jewish holiday celebrated on the 14th of the month of Adar. It usually falls out sometime in March on the secular calendar. It is a festival celebrating the hidden miracle of the Persian Jews being saved from extermination by Haman.
Every month has either 29 or 30 days. (one month 29, the next 30). There are 12 months altogether but once every 3-4 years, another month is added so that the Jewish holidays always fall in the right time since the Hebrew calendar is both by the moon and sun (Passover in spring etc.) The calender is from right to left as the Jews write from right to left.
In Israel, both the Jewish and the Gregorian calendar have legal status. Other countries do not use the Jewish calendar, though many Western countries recognize its status among the Jews. For example, a Jew in those countries might not be penalized if he/she misses a test on a Jewish holy day.
Pessach lasts lasts seven days, except for orthodox Jews (in Diaspora). For them it lasts eight days. It happens between 15. und 22. Nisan (a month in the Jewish calendar)
The Jews' calendar was better.Answer:Most of the Western world uses a solar calendar, in which the lunar phases are a mere curiosity. Islam takes a different approach, using a calendar which is exclusively lunar. The Jewish calendar is lunisolar; meaning that the months are lunar months but the holidays always come out in their specified solar seasons. This is done by adding a leap-month every second or third year.
This question does not have one right answer.Christmas is celebrated by Christians, who traditionally use the widely accepted solar calendar. This is the one that is sold in most stores. (12 months, January, February, etc)Hanukkah is celebrated by Jews, and the Jewish religion determines its holidays according to a lunar calendar. The lunar and solar calendars are different, and this is why the dates of Jewish holidays change every time the solar calendar restarts.In most cases, both holidays happen to fall in the month of December. However, since Hanukkah's date is constant according to the lunar calendar, occasionally, Hanukkah falls on November, such as in 2013.
Jews pray every day; but you probably refer to Yom Kippur, which has much lengthier prayers than any other day. It is the 10th of Tishrei in the Jewish calendar.
Food, and if they are observant Jews, kosher food. There are two fast days in the Jewish calendar when Jews do not eat anything. Perhaps these are the "non regular days" to which the question refers. These are Yom Kippur and Tisha B'Av.
The Hebrew calendar. It has twelve lunar months, generally alternating 29 or 30 days per month; and a leap month is added every 2 or 3 years in order to keep our lunar months in step with the solar seasons.