Av (Hebrew: אָב‎, Standard Av Tiberian ʾĀḇ Aramaic אבא Abba; from Akkadian abu; "father") is the eleventh month of the civil year and the fifth month of the ecclesiastical year on the Hebrew calendar. The name is Babylonian in origin and appeared in the Talmud around the 3rd century. This is the only month which is not named in the Bible. It is a summer month of 30 days. Av usually occurs in July–August on the Gregorian calendar.
The Babylonian Talmud, Taanit 29a, states that "when we enter [the month of] Av, our joy is diminished". This is because the darkest events in Jewish history occurred during the first week and a half of this month, particularly The Nine Days which culminate in Tisha B'Av, the 9th of Av. However, there is a minor and largely unknown holiday during the full moon of the month called Tu B'Av which was, in ancient times, one of the happiest days of the year.
The month is also sometimes referred to as Menachem Av (Hebrew: מנחם אב‎) (Av of Comfort or Comforter of Father(s)), but most only use this title in the sanctification of the month recited on the Shabbat before Rosh Chodesh and following Tisha B'Av.