Jewish calendar, also known as the Hebrew calendar is the yearly calendar that is followed in Judaism. The calendar determines the important dates, the Jewish Holidays and the correct Torah portions for the people to read them. The Calendar also determines the Yahrzeits, which are the dates to honour the death of the relatives and the precise dates for Psalms that are read by the people customarily.
There have been two different forms of the calendar that have been used. One of them was an observational form used before the annihilation of the Second Temple in 70 CE, which was based on the observation of the phases of the moon. The other form of the calendar was rule-based which was described by the Maimonides at first in 1178 CE. The latter was accepted during a period of transition between 70 and 1178 CE.
The modern version of the Hebrew calendar is determined by arithmetic calculations and is a lunisolar calendar. Since there is roughly a difference of 11 days between 12 lunar months and a single solar year, the Hebrew calendar repeats itself in a Metonic cycle that consists of 235 lunar months. An additional lunar month is placed after a period of every two-three years that sums up to 7 times in a span of 19 years.
The Jewish calendar works the same way as an ordinary 7-day weekly cycle. All the days are named in Hebrew and names that have been given to the weekdays are just the number of the days within the week. For example, Yom Rishon means "the first day", which is Sunday. Similarly, Yom Sheini is the "second day", Yom Shlishi is the "third day", Yom Rivii is the "fourth day", Yom Chamishi is the "fifth day", Yom Shishi is the "sixth day" and lastly the Yom Shabbat which means the "seventh day" and is equivalent to Saturday.
|Tish'a B'Av||Aug 14|
|Rosh HaShanah||Oct 3-4|
|Yom Kippur||Oct 12|
|Shmini Atzeret||Oct 24|
|Simchat Torah||Oct 25|
|Chanukah||Dec 25-Jan 1|