Answer:
   
   Note: This is based on material at
   [5]http://www.rrz.uni-hamburg.de/rz3a035/jew_fest.html.
   
   The Jewish calendar has its months determined on a lunar basis, and
   its years on a solar basis. As the lunar year consists of about 354
   days and the solar year has 365.25 days, the lunar cycle must be
   adjusted to the solar calendar in order that Passover should always
   fall in the "month of Abib" (Deut. 16:1). This adjustment is made by
   having a leap year seven times in each nineteen-year cycle;
   specifically, in the 3rd, 6th, 8th, 11th, 14th, 17th, and 19th years
   of the cycle. In a leap year, an extra month of Adar (Adar Sheni) is
   added into the calendar.
   
   The months in the Jewish calendar are as follows:
     * Nisan. The first month of the Jewish calendar (Ex. 12:2); the
       seventh from the beginning of the civil year. The name appears in
       the Bible only in Esther 3:7 and Nehemiah 2:1. In Ex. 13:4, 23:15,
       34:18; Deut. 16:1, it is called "the month of Abib (Spring).
       According to one tradition, the Creation occured in the month of
       Nisan. It is also the month in which the biblical patriarchs were
       born, Moses led the Jews out of Egypt, and the final redemption is
       to take place (TB. RH 11a). In biblical times, kings reckoned the
       years of their reign from the first of Nisan. It is customary
       during the entire month of Nisan to refrain from reciting tahanun
       (supplication) prayers, eulogies and memorial prayers. Notable
       holidays are Pasover (15-21/22), Holocaust Memorial Day (27).
       Historically, the Tabernacle was completed in the wilderness on
       the 1st; the Paschal sacrafice was offered in biblical times and
       the Warsaw Ghetto Revolt in 1943 began on the 14th.
     * Iyyar. The Bible calls this month Ziv (radience) (I Kg. 6:1,
       6:37), and it is referred to as Iyyar in the Talmud (RH 1:3).
       Notable Holidays are Israeli Independence Day (5), Lag b'Omer
       (18), and Yom Yerushalayim (28).
     * Sivan. The name appears in the Bible only in Esther 8:9. Notable
       holidays are Shavuot (6/7).
     * Tammuz. Tammuz is mentioned once in the Bible in reference to the
       Babylonian god (Ezek. 8:14); in the Talmud it appears frequently
       as the name of the month. Notable holidays are the Fast of Tammuz
       (17).
     * Av. Av first appears in Jewish sources in Megillat Ta'anit of the
       talmudic period, but appears earlier in Assyrian inscriptions,
       apparently referring to spring and meaning "fresh growth". As many
       national calamities occured in Av, it is also called Menahem
       (consoler), expressing the hope it will be a month of consolation.
       "When Av arrives, gladness is diminished," say the talmudic sages
       (Ta'an. 4:6). Hence, celebration is severely curtailed until after
       the ninth of Av. During these nine days, amusements, bathing for
       pleasure, business dealings, new construction, planting and
       nonvital repairs are avoided; meat is not eaten and wine not drunk
       except on Sabbath and at a se'udat mitzah repast. Notable holidays
       are Tish b'Av (9). Notable historic events: Aaron died on the 1st;
       on the 9th: the First Temple was destroyed (586 BCE); the Second
       Temple was destroyed (70 CE); Jerusalem was razed by Hadrian (132
       CE); Bethar fell as the Bar Kokhba revolt was crushed (135 CE);
       England expelled the Jews (1290 CE); Spain expelled the Jews (1492
       CE); and the Jews of Rome were enclosed in a ghetto (1555 CE); on
       the 10th, France expelled the Jews (1306 CE).
     * Elul. As Elul immediately precedes the Days of Awe, it is a month
       of repentence in which special prayers are said and the shofar is
       sounded at the weekday morning service. In the Sephardi rites,
       selihot are recited daily throughout the month, whereas Ashkenazim
       recite them only during the week before Rosh ha-Shanah.
     * Tishri. In the Torah, Tishri is referred to as "the month of
       Ethanim", the month of natural forces (I Kg. 8:2). The expression
       is possibly a reference to the winds that are expected to bring
       the season's first rains, or to the torrents that are supposed to
       fill the wadis in Eretz Israel at this time of year. The name
       "Tishri", from the Akkadian root meaning "to begin", first appears
       in Jewish sourses in the Talmud. Notable holidays are Rosh
       Ha-Shana (1/2), Fast of Gedaliah (3); Yom Kippur (10); Sukkot
       (15-22); Hoshana Rabbah (21); Shemini Atzertet (22); Simchat Torah
       (23). Notable historic events: on the 10th, the Jews were expelled
       from Paris (1394 CE) and the Yom Kippur War began (1973 CE).
     * Heshivan. The Torah calls it "the month of the Bul" (I Kg. 6:38)
       in reference to the bountiful harvests associated with the season.
       The name Heshivan first appears in Jewish sourses in talmudic
       literature and Josephus (Ant. 1,3,3). It is often referred to as
       Marheshivan, i.e. with the prefix "mar". The term "mar" is thought
       to mean "a drop" and relates to the month as the beginning of the
       rainy season. There are no festivals or fast days in Heshivan. In
       that respect it is unique. Notable historical days: On the 16th,
       Kristallnach, the the destruction of synagogues in Nazi Germany
       and Austria, occured.(9/10 November 1938).
     * Kislev. Kislev is mentioned in the Torah (Zech. 7:1; Neh. 1:1).
       According to the Talmud, "If rains have not fallen by the 1st of
       Kislev, three public fasts are decreed" (TB. Ta'an. 10a). Notable
       holidays: Chanukkah (starts on the 25th). Notable historical
       events: on the 17th, the U.N. General Assembly decided on
       partition of Palestine (29 November 1947); on the 22nd, the State
       of Israel declared Jerusalem its capital (1949); and on the 24th,
       the building of the Second Temple occurred (Haggai 2:18) and the
       British captured of Jerusalem (8 December 1917).
     * Tevet. Although it is mentioned in the Torah its meaning is
       obscure (Esth. 2:16). The last two or three days of Hanukkah fall
       at the beginning of Tevet. Notable Holidays: Asarah be-Tevet (10),
       a day of fasting and mourning, marking the start of the siege of
       Jerusalem by the Babylonian King Nebuchadnezzar (588 BCE); this
       day is also the Memorial day for the victims of the Holocaust
       whose day of death is unknown, set by the Israeli Chief Rabbinate
       (1949). Notable historical events: on the 19th, Keren Kayemet
       le-Israel (Jewish National Fund) was established, (1901 CE); on
       the 20th, Maimonides died (1204 CE); and on the 23rd Portugal
       expelled its Jewish population (1496).
     * Shevat. The name appeared once in the Torah (Zech. 1:7). Notable
       holidays: Tu b'Shevat (15), the New Year for Trees. Notable
       historical events: on the 15th, the First Knesset convened (1949);
       and on the 18th, the Knesset elected Chaim Weizmann as first
       president of the State of Israel.
     * Adar/Adar II. The name appears in the Torah in Ezra 6:15 and seven
       times in Esther. In a leap year, the intercalcated month is called
       Adar Sheni (Second Adar or Adar II) and the regular month Adar
       Rishom (First Adar or Adar I). Events normally occuring in Adar
       are celebrated in Adar II; however, the yahrzeit of someone who
       died in an ordinary Adar is marked in Adar I (although, because
       there is a difference of opinion, some will say Kaddish also in
       Adar II). "When Adar arrives people should increase gladness" (TB.
       Ta'an. 29a) because of the Purim deliverance that occured in that
       month. In Adar the half shekel was collected from the public for
       Temple and related purposes; the forbidden kilayim grafted crops
       were uprooted; repairs were begun on roads and on water sources
       damaged by rain, to make them fit for the Passover pilgrims to
       Jerusalem. Notable holidays are the Fast of Esther (13); Purim
       (14); and Shushan Purim (15). Notable historic events include on
       the1st, the Shekel campaign begun in Temple period; and on the
       7th, the supposed date of the birth and death of Moses, which is
       marked as a yahzeit of all persons whose burial place is unknown,
       and, in Israel, of the "Unknown Soldiers."