Yizkor is our public observance of the loss of a loved one. The word yizkor (יִזְכּוֹר - literally, “may He remember”) is our calling upon God to remember the souls of our lost loved ones.
Generally we have a Yizkor service four times a year - on Yom Kippur, the eighth day of Sukkot (Shemini Atzeret), the last day of Passover, and the second day of Shavu’ot, amounting to once per festival plus once on the High Holidays. (In Israel it is similar, with some on different days.) It is thought that the Ashkenazi custom of reciting Yizkor on the festivals dates to the era of the Crusades, when so many communities were being massacred. Prior to that, the Midrash Tanchuma (composed in Talmudic Babylon/Italy/Israel around 500-800 CE) cites the custom of remembering the departed and pledging charity on their behalf on Yom Kippur.
Those who have lost a parent or other loved one participate in the Yizkor service. (Some authorities hold that during the first year after the death of the person, one would not participate; others see no reason not to do so.) There is a negative and detrimental old-fashioned non-rabbinic custom that one should not remain in the room during the Yizkor service if one’s parents are still alive, lest they die within the year. Your correspondent (who said Yizkor for her brother while her parents were alive) has long opined this was created and put forth by a teenager who wished instead to roam the building rather than stay in services.
Yizkor often begins with opening readings, sometimes including Psalm 91, leading into the main portion in which first we individually ask God to remember our loved ones, offering the quid pro quō of giving charity so God will bind the loved ones’ souls in the bonds of life eternal. This usually is followed by the congregation recalling the six million who perished in the Holocaust and various other victims of horrible multiple deaths, culminating with the E‑l Malei Rahamim (Rabbi Daniel Yolkut of Poale Zedeck created a fine new version for The Eleven), which may be followed by yet another mass-murder prayer, the Av HaRahamim (Ancestor of Mercies) which eulogizes communities destroyed in the 1096 Crusades. There may then be a recitation or chanting of Psalm 23.
Yizkor candles, usually in a tall glass, may be lit at home for any day containing a Yizkor service. And many communities for many centuries have created books of remembrance for these occasions. The books, sometimes the only remnant of a community, have become a treasure trove for genealogists. Here’s a tip of our hat to Aviva Lubowsky and her team who create Beth Shalom’s Book of Remembrance.