The Kaddish is a prayer in flux. What began as a prayer recited following the study of Torah, has become a prayer with multiple versions (Half Kaddish, Full Kaddish, Siyyum Kaddish, etc), recited during daily tfillah and other occasions.
The earliest form of the Kaddish dates to the Second Temple. The version we know as the Mourner’s Kaddish and the related practice of reciting it for a defined period is from 12th century Ashkenaz. During that period, Jews began to believe that the recitation of the Mourner’s Kaddish (typically by a son of the deceased) could help alleviate the pains that a loved one experiences for up to 12 months in Gehenna following their passing.
For all relatives other than parents, one is obligated to recite Mourner’s Kaddish during the Shloshim period of mourning (typically thirty days); while for parents the obligation is for 11 months.
Like most mitzvot, the obligation to recite Mourner’s Kaddish is non-transferable. Just as one cannot pay another to keep kosher for her or to recite the Sh'ma instead of her, one’s obligation to recite Kaddish cannot be sold.
Nevertheless, following our ancestors from nearly a millennia ago, many Jews find comfort in knowing that Mourner’s Kaddish is being recited in memory of their loved one. Similarly, supporting a synagogue through tzedakah given in the name of a loved one, we believe allows for aliyat haneshamah (the elevation of the soul).
At Adath Israel, a list of names for whom tzedakah is given for the recitation of the Mourner’s Kaddish is present on the bimah in the Donnenfield Chapel and Main Sanctuary. The clergy leading the service sees the names and keeps them in mind when s/he recites Mourner’s Kaddish.
