Yahrzeit is the commemoration of the death of a Jew by a mourner (the child, sibling, spouse or parent of the deceased). The Yahrzeit date, which is calculated according to the Hebrew calendar, is the anniversary of the death, not the burial.
It is on this day that we light a Yahrzeit candle to honor the memory of the loved one who has passed away. Traditionally, the Yahrzeit prayer, which is the Mourner’s Kaddish is recited and the special memorial candle that burns for 24 hours is lit. The Yahrzeit candle should be lit after dark on the evening before the anniversary of the death and burn for a full 24 hours.