Each year, on the (Hebrew calendar) anniversary of a death, a day of remembrance is observed by the immediate relatives. In Yiddish, it is known as yahrtzeit, which merely means "a year’s time." On that day, the memory of the deceased is honored in three ways.
As evening falls, a candle is kindled. The familiar candles burn for twenty-five hours (or more), and represent the spark of life which remains present in our hearts long after death has taken away physical existence. Interestingly enough, no formal ritual exists for lighting this candle. Many meditations have been composed for the purpose. I always find it comforting to talk with my father for a few minutes, and sometimes more than once during the course of the day.
Kaddish is recited at minyan during each service that day, beginning at ma’ariv. Some people confuse the fact that we read a list of upcoming yahrtzeits on Friday nights with the observance itself. Instead, the announcement is made to remind the mourners and the congregation to remember their loved ones.
Acts of righteousness are performed to honor the memory of the dead. Typically, survivors should give tzedakah that day and study at least a small section of sacred literature. Of course, if the observance is on Shabbat or a festival, then tzedakah should be given at another time.
These three customs are also observed on the four days that communal memorial prayers are recited. The service known as yizkor ("may God remember") is included on Yom Kippur, Shemini Atzeret, and the last days of Pesach and Shavu’ot. Only one candle need be kindled for all loved ones on those evenings, though many people light separate candles for each person remembered.
Many superstitions abound about yizkor, including the notion that one should not attend if one or both parents are still alive. Intellectually, we know that superstitions are foolish, but personal customs are hard to change. Still, the person who avoids yizkor avoids the inevitable when it might be appreciated and learned in untroubled circumstances.