Yahrtzeit

Yahrtzeit, means "Time (of) Year" in Yiddish

The word is also used by non-Yiddish-speaking Ashkenazi Jews, and refers to the annual anniversary of the day of death of a relative. Yahrtzeit literally means "time of [one] year".

Mourners required to fulfill this observance are the children, siblings, spouses and parents of the deceased. The custom is first discussed in detail in Sefer HaMinhagim (pub. 1566) by Rabbi Isaac Tyrnau.

The Yahrtzeit falls annually on the Hebrew date of the deceased relative's death according to the Hebrew calendar.
The main halakhic obligation is to recite the mourner's version of the Kaddish prayer three times (evening of the previous day, morning, and afternoon), and many attend synagogue for the evening, morning, and afternoon services on this day. (During the morning prayer service the mourner's Kaddish is recited at least four times.) As a widely practiced custom, mourners also light a special candle that burns for 24 hours, called a "Yahrzeit candle". Lighting a yahrtzeit candle in memory of a loved one is a minhag ("custom") that is deeply ingrained in Jewish life honoring the memory and souls of the deceased.

Strict Jewish law requires that one should fast on the day of a parent's Yahrzeit, although this is not required, some people do observe the custom of fasting on the day of the Yahrtzeit. Among many Orthodox Jews it has become customary to make a siyum by completing a tractate of Talmud or a volume of the Mishnah on the day prior to the Yahrtzeit, in the honor of the deceased. A halakha requiring a siyum ("celebratory meal"), upon the completion of such a study, overrides the requirement to fast.

Jewish mourners are required to commemorate the death of a first-relative: mother, father, brother, or sister. The main halakhic obligation is to recite the mourner's version of the Kaddish prayer at least three times, Maariv at the evening services, Shacharit at morning services, and Mincha at the afternoon services.

Many synagogues will have lights on a special memorial plaque on one of the synagogue's walls, with names of synagogue members who have died. Each of these lights will be lit for individuals on their Yahrzeit, and all the lights will be lit for a Yizkor service.

Some have a custom to visit the cemetery on fast days (Shulchan Aruch Orach Chayim 559:10) and before Rosh Hashanah and Yom Kippur (581:4, 605), when possible, and for a Yahrzeit. During the first year the grave may be visited on the shloshim, and the yartzeit.

Even when visiting Jewish graves of someone that the visitor never knew, he or she may place a small stone at the graveside. This shows that someone visited the graveside, and represents permanence. Leaving flowers is not a traditional Jewish practice. Another reason for leaving stones is tending the grave. In Biblical times, gravestones were not used; graves were marked with mounds of stones (a kind of cairn), so by placing (or replacing) them, one perpetuated the existence of the site. This was also helpful for Cohanim, who needed to avoid spiritual impurity that could be passed on by corpses/graves.