Yahrzeit means "Time (of) Year" in Yiddish and refers to the anniversary of the day of death of a relative. The commemoration is known in Hebrew as nachala ("legacy," or "inheritance"). This term is used by most Sephardic Jews, although some use the Ladino terms meldado or less commonly, anyos ("years"). It is widely observed, and based on the Jewish tradition that mourners are required to commemorate the death of a relative. The yahrzeit falls annually on the Hebrew date of the deceased relative's death according to the Hebrew calendar.
Jews are required to commemorate the death of parents, siblings, spouses, or children. The main halachic 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.
As a widely practiced custom, mourners also light a special candle that burns for 24 hours, called a "yahrzeit candle". Lighting a yahrzeit 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 yahrzeit, or at least refraining from meat and wine, and refrain from going to joyous musical events.
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.
Yizkor - In addition to the observance of the yahrzeit, Yizkor prayers are recited four times a year, and are intended to be recited in a synagogue with a minyan; if one is unable to be with a minyan, one can recite it without one. These four Yizkor services are held on Yom Kippur, Shemini Atzeret, on the last day of Passover, and on the second day of Shavuot. In the Yizkor prayers God is asked to remember and grant repose to the souls of the departed.