Jewish Year

The Jewish Year

A lunar year has twelve months of either 29 or 30 days each, which yields a 354-day year. To ensure the same festivals always fall in the same season each year, an additional month (Adar II) is added seven times in every nineteen years to make up the difference.
Determining what marks a new year is a bit complicated. Based on Exodus 12:2, Nisan is considered the first month of the year. However, the year number changes on Rosh Hashanah, which is on the first of Tishrei, the seventh month of the religious year. Then there is Tu B'Shvat (15 Shvat), which is the new year "for trees."
The best way to understand this is that the Jewish calendar simply has different "years" for different purposes, just as the secular world recognizes as fiscal year, a school year and a calendar year. The bottom line: Nisan is the first month on the Jewish calendar and Rosh Hashanah (on 1 Tishrei) is the "Jewish New Year."
The year number on a Jewish calendar is based on a traditional date of creation, based on adding up the geneaologies in the Tanakh. The Jewish year 5764 began on September 27, 2003. For convenience, many Jews use the Christian dating of years, but with the designation CE (Common or Christian Era) instead of AD (anno domini, "in the year of our Lord"). To use the latter expression, even in abbreviation, would be to falsely (and blasphemously) imply faith in Jesus as Lord.

Jewish Months

Each Jewish month begins with the new moon, which is called the Rosh Khodesh (Head of the Month). Rosh Khodesh was a major holiday in the First Temple period, celebrated with special sacrifices and feasts, but it was downgraded to a minor holiday after the Babylonian exile and not generally recognized today. {1}
The months of the Jewish calendar are as follows:

	Number of Days	Gregorian Equivalent	Holidays in This Month
Nisan	30	March-April	Passover (15th)
Iyar	29	April-May
Sivan	30	May-June	Shavuot (6th)
Tammuz	29	June-July
Av	30	July-August	Tisha b'Av (9th)
Elul	29	August-September
Tishri	30	September-October	Rosh Hashanah (1st) Yom Kippur (10th) Sukkot (15th)
Kheshvan	29 or 30	October-November
Kislev	29 or 30	November-December	Hanukah (25th)
Tevet	29	December-January
Shevat	30	January-February	Tu b'Shevat (15th)
Adar	29 (30 in a leap year)	February-March	Purim (14th)
Adar II	(29 in a leap year)	March-April	Purim (14th; leap year only)

Jewish Days

Finally, the Jewish day begins and ends at sunset. Thus the Sabbath begins not at midnight Saturday morning but on Friday at sundown and the first Hanukkah candle is lit on the night of 24 Kislev.