Kaddish (קדיש, Qaddish Aramaic: "holy"; alternate spellings, qaddish, ḳaddish) is a prayer found in the Jewish prayer service. The central theme of the Kaddish is the magnification and sanctification of God's name. In the liturgy different versions of the Kaddish are used functionally as separators between sections of the service. The term "Kaddish" is often used to refer specifically to "The Mourners' Kaddish", said as part of the mourning rituals in Judaism in all prayer services as well as at funerals and memorials. When mention is made of "saying Kaddish", this unambiguously denotes the rituals of mourning.

The opening words of this prayer are inspired by Ezekiel 38:23, a vision of God becoming great in the eyes of all the nations. The central line of the Kaddish in Jewish tradition is the congregation's response: יְהֵא שְׁמֵהּ רַבָּא מְבָרַךְ לְעָלַם וּלְעָלְמֵי עָלְמַיָּא (Yehei shmëh rabba mevarakh lealam ulalmey almaya, "May His great name be blessed for ever, and to all eternity"), a public declaration of God's greatness and eternality. This response is an Aramaic translation of the Hebrew "ברוך שם כבוד מלכותו לעולם ועד" (Blessed be His name, whose glorious kingdom is forever), which is to be found in the Jerusalem Targum (יְהֵא שְׁמֵיהּ רַבָּא מְבָרֵךְ לְעָלְמֵי עַלְמִין) (Genesis 49:2 and Deuteronomy 6:4), and is similar to the wording of Daniel 2:20.

While the term Holocaust victims generally refers to Jews, the Nazis also persecuted and killed millions of members of other groups they considered inferior (Untermenschen), undesirable or dangerous.

The United States Holocaust Memorial Museum (USHMM) states: “The Holocaust was the murder of six million Jews and millions of others by the Nazis and their collaborators during World War II."

In addition to Jews, the targeted groups included Poles (of whom 2.5 million gentile Poles were killed) and some other Slavic peoples; Soviets (particularly prisoners of war); Romanies (also known as Gypsies) and others who did not belong to the "Aryan race"; the mentally ill, the deaf, the physically disabled and mentally retarded; homosexual and transsexual people; political opponents such as social democrats and socialists; and religious dissidents, i.e. members of Jehovah's Witnesses and Catholics. Taking into account all of the victims of Nazi persecution, they systematically killed an estimated six million Jews and mass murdered an additional eleven million people during the war. Donald Niewyk suggests that the broadest definition, including Soviet civilian deaths would produce a death toll of 17 million.