Yizkor is an Ashkenazi Jewish memorial prayer service for the dead. The word "Yizkor" means "may . It is recited four times a year in most Ashkenazi communities: on Yom Kippur, on the final day of Passover, on the second day of Shavuot, and on Shemini Atzeret. In Sephardic custom, there is no Yizkor prayer, but the hashkavot serve a similar role in the service. The Yizkor prayers are intended to be recited in a synagogue with a minyan, but if one is unable to be with a minyan, one can recite it without one.

The earliest source of Yizkor is the Midrash Tanchuma, which mentions the custom of remembering the deceased and pledging charity on their behalf on Yom Kippur. According to the Sifre, reciting Yizkor on Yom Kippur achieves atonement for those who have died. The service was popularized amid the persecution of Jews during the Crusades.

Customs associated with Yizkor include leaving the main sanctuary during the Yizkor service out of respect or superstition, and reciting the names of departed relatives during the service. It is usually not attended within the first year of mourning, until the first yahrzeit has passed.

Yizkor is founded on two fundamental Jewish beliefs: that the prayers and actions of people in this world can have an elevating spiritual effect on the souls of the departed, and that a primary, God-given mission in every persons life is to make the world a kinder, better, more beautiful place. The central element of Yizkor is the commitment to make a charitable donation in honor of ones departed relative. By making such a commitment, one affirms the belief that God wants us to do what we can to be helpful and alleviate the suffering of others.