Yom Kippur is the holiest day in the Jewish calendar, and it is appropriate to greet people warmly when you meet them. The most common Jewish greeting on Yom Kippur is "g’mar chatima tovah" (pronounced gih-MAR chah-tee-MAH toe-VAH), which literally means "a good final sealing." This greeting references the traditional belief that a person’s fate for the coming year is written on Rosh Hashanah and sealed on Yom Kippur. This greeting can be used in the run-up to Yom Kippur and in the early hours of the fast itself.

Another Yom Kippur greeting, often used in the days preceding the fast or just as it’s beginning is "tzom kal" (pronounced tzome kahl), which literally means "easy fast." The English equivalent, "Have an easy fast," is also not uncommon. Recognizing that the purpose of Yom Kippur is not that the fast should be easy per se, some have taken instead to wishing people a meaningful fast. All three variants are acceptable.

Other generic Jewish holiday greetings are also used on Yom Kippur, including "chag sameach" (pronounced chahg sah-MAY-ach), which literally means "happy holiday," "gut yontiff" (pronounced goot YUHN-tiff), which is a yiddishized version of the Hebrew phrase "yom tov," literally meaning "good day" and referring to any major Jewish holiday on which work is traditionally forbidden.

In English, the best greeting to give to someone observing Yom Kippur is "have an easy fast." For those who are not fasting but are observing Yom Kippur, you can wish them a "Good Yuntif" or "Yom Tov," which are Yiddish and Hebrew, respectively, for "Have a good holy day." A more traditional greeting, and one specific to Yom Kippur, is "Gmar hatimah tovah," or "Gmar tov," which roughly translates to "a good seal." Those observing the holiday believe that the book of life, which determines an individual’s fate for the coming year, opens on Rosh Hashanah and is sealed at the end of Yom Kippur following the period of repentance.