In anticipation of Yom Kippur, which lasts exactly 25 hours beginning tomorrow evening, here is the latest addition to your friendly neighborhood Holiday Cheat Sheet.

Holiday: Yom Kippur (pronounced Yom Ki-POOR)

AKA: The Day of Atonement

Religion Represented: Judaism

Date: The 10^th day of Tishrei in the Hebrew calendar. In 2012, Yom Kippur lasts from from Sept. 25 at sunset to Sept. 26 at nightfall.

Not To Be Confused With: Rosh Hashanah, the Jewish New Year.

On a Scale of 1 to 10: Yom Kippur is a heavy 10.

What It Is: Yom Kippur is the last and most important of Judaism’s 10 High Holy Days, which begin on Rosh Hashanah, the Jewish New Year. As you might recall, the New Year is a time to reflect on one’s life and resolve to be a better person in the coming year. On Yom Kippur, which occurs 10 days later, God is said to take a look at the deeds of the Jewish people and to seal each person’s fate in the “Book of Life.” More than anything, Yom Kippur is a day of seeking forgiveness and giving to charity.

Associated Literary Passages: Leviticus 16:29 and 23:27; Numbers 29:7-11 and Mishnah Tract Yomah 8:1

The Sabbath of All Sabbaths: Saturday (“the sabbath”) is to Jews what Sunday is to Christians; it is the “day of rest” when synagogues hold their weekly worship services. Yom Kippur is considered the “Sabbath of all Sabbaths” because, not only is it a day of complete rest (no work, no driving, etc.) but it’s a day of fasting and other restrictions: no washing or bathing, no perfumes or deodorants, no wearing leather shoes, and no sex. Services run all day on Yom Kippur — from 8 a.m. to 6 p.m. — with a break around 3 p.m. People wear white, and services generally end with a long blow from the shofar.

Coolest Thing about Yom Kippur: During their ever-so-long day of synagogue services (decidedly NOT the coolest thing about Yom Kippur, given the no-deodorant rule), participants take part in a “group confession.” They confess to being aggressive, slanderous, acting callously, and a number of other things — usually involving behaving badly toward others in speech or deed. The cool thing is that the sins are confessed in the plural — “we” have done this, “we” have done that — emphasizing “communal responsibility for sins.” Now, I don’t believe in “sins,” per se, and I know that, in this sense, they are only talking about the Jewish people. But I think if more human beings could adopt even a little of this attitude, “we” could kick up the world’s compassion level a notch or two.

Appropriate Greeting: ”Have an easy fast” (“Happy Yom Kippur” is not considered appropriate, as Yom Kippur is not a happy holiday.)