The month of Tishri, which falls during the months of September and October on the Gregorian calendar, is probably the busiest time of the year for Jewish holidays. In the month of Tishri, there are a total of 13 days of special religious significance, 7 of them holidays on which work is not permitted.
These holidays include the holidays known as the "High Holidays," the most important holidays of the Jewish year: Rosh Hashanah and Yom Kippur. A 2000 survey showed that only 46% of all Jews affiliate themselves with a synagogue, but 59% fast on Yom Kippur. If a Jew ever goes to synagogue (other than for weddings or bar mitzvahs), it is for these holidays.