Historical significance

There is no way to know exactly how early Tu B'Av began.The fifteenth day of Ab was a popular holiday during the second Temple. The holiday celebrated the wood-offering brought in the Temple.

Unmarried girls would dress in simple white clothing (so that rich could not be distinguished from poor) and go out to sing and dance in the vineyards surrounding Jerusalem.The Talmud states that there were no holy days as happy for the Jews as Tu B'Av and Yom Kippur.Various reasons for celebrating on Tu b'Av as cited by the Talmud and its commentators:While the Jews wandered in the desert for forty years, female orphans without brothers could only marry within their tribe, to prevent their father's inherited land in the Land of Israel from passing on to other tribes. On the fifteenth of Av of the fortieth year, this ban was lifted.Tribes of Israel were permitted to mingle with each other," namely: to marry women from other tribes (Talmud, Taanit 30b). This Talmudic source probably is alluding to a story in the book of Judges (chapter 21): After a civil war between the tribe of Benjamin and other Israelite tribes, the tribes vowed not to intermarry with men of the tribe of Benjamin.That same year, the last of the generation of the sin of the spies, which had been forbidden to enter the Promised Land, died out.Cutting of the wood for the main altar in the Temple was completed for the year.

Tu B'Av is both an ancient and modern holiday.

Originally a post-biblical day of joy, it served as a matchmaking day for unmarried women in the second Temple period (before the fall of Jerusalem in 70 C.E). Tu B'Av was almost unnoticed in the Jewish calendar for many centuries but it has been rejuvenated in recent decades, especially in the modern state of Israel.

It is gradually becoming a Hebrew-Jewish Day of Love, slightly resembling  Valentine's Day  .It should be noted that Tu B'Av, like several Jewish holidays (Passover, Sukkot, Tu Bishvat) begins on the night between the 14th and 15th day of the Hebrew month, since this is the night of a full moon in our lunar calendar. Linking the night of a full moon with romance, love, and fertility is not uncommon in ancient cultures.For almost 19 centuries--between the destruction of Jerusalem and the re-establishment of Jewish independence in the state of Israel in 1948--the only commemoration of Tu B'Av was that the morning prayer service did not include the penitence prayer (Tahanun).In recent decades Israeli civil culture promotes festivals of singing and dancing on the night of Tu B'Av.