The Hebrew calendar is used by the Jews, most commonly for religious purposes. It is based on the rotation of the Earth about its own axis, the moon's revolution around the axis of the Earth and the Earth's revolution around the Sun. The lengths of the years in a Hebrew calendar vary in a cyclic manner, owing to the differences in the lunar months and a solar year. This calendar has different starting points for different purposes like civil and religious (for e.g. in the Gregorian calendar the financial year begins in March). Let us look at the months that comprise one year of the Hebrew calendar. Nissan: It has 30 days and is considered equivalent to the months of March and April of the Gregorian calendar. Fast of the Firstborn, a unique day of fasting and Passover that is celebrated in memory of God who saved the Jews, are the major festivities in this month. Iyyar: The length of this month of the Hebrew calendar is 29 days. The name of this month has a Babylonian origin. It is equivalent to the months of April and May of the Gregorian calendar. Its Hebrew name is Ziv. The second Passover that falls on the 14th day of the month is an important holiday in Iyyar. Memorial day observed on the 4th of Iyyar and the Israeli Independence Day on the 5th are other major holidays in this month. Sivan: It is a 30-day month of the Hebrew calendar and equivalent to May and June of the Gregorian calendar. Shavuot falling on the 6th of this month is observed in memory of the anniversary of the day when God gave Ten Commandments. It is a major holiday in this month. Tammuz: The name is derived from the Babylonian God, named Tammuz. It is of 29 days and equivalent to June and July of the Gregorian calendar. The 17th of this month is observed as a fast day, in memory of Jerusalem's walls being laid down. Av: It is a 30-day long month and July and August are its Gregorian equivalents. Its name has a Babylonian origin, with Abu, its Babylonian equivalent. The Fast of Tisha B'Av is an important festival observed in this month. Elul: It is a summer month, which is 29 days long. It corresponds to the months of August and September of the Gregorian calendar. During this month, many Jews visit the graves of their near ones to commemorate their past. It is a custom to write letters carrying new year wishes during this month. Tishri: This month is of 30 days and its Gregorian equivalents are September and October. It experiences autumn for most of its days. Rosh Hashanah, known as the Jewish New Year and Sukkot, a Biblical pilgrimage festival, are the important days of the month of Tishri. Cheshvan: This month corresponding to the Gregorian months of October and November has 29 or 30 days. The Ethiopian Jewish people celebrate Sigd on the 29th day of Cheshvan in honor of the acceptance of Torah, the religious writings of Judaism. Kislev: It is a 30-day-long autumn month. Its Gregorian equivalents are the months of November and December. Hanukkah, a festival that lasts for eight nights begins from the 25th of this Hebrew month. Tevet: This is a month of 29 days and is equivalent to the Gregorian months of December and January. The festival of Hanukkah continues through some part of this month. The Tenth of Tevet or the tenth day of Tevet, is observed as a fast day. Shevat: A winter month of 30 days, Shevat, falls in the Gregorian months of January and February. Tu Bishvat, a Jewish holiday that marks the New Year of the Trees, is celebrated in this Hebrew month. Adar: It consists of 29 days of winter. It follows the month Adar Aleph. The Fast of Esther on the 11th of Adar and Purim celebrated on the 14th day of this month are among the important festivals that fall in Adar. This was a list of the months of the Hebrew calendar. True, the Hebrew calendar is used only for religious purposes today, but it is nonetheless important to understand that the Gregorian calendar, which is used as a standard today, is in some way linked to the ancient Hebrew calendar. Understanding this closely-knit relationship is important and interesting.