Memorial customs, including lighting a yizkor (memorial) candle and joining in congregational Yizkor memorial) prayers on Yom Kippur and on the last days of Sukkot, Pesach (Passover), and Shavuot, are customarily observed in memory of one’s parents, siblings, spouses, and children. Some Reform Jews choose to observe memorial customs for other relationships as well.
One also lights a candle on the yahrzeit or anniversary of the loved one’s death. The memorial candle is lit just before the start of the yahrzeit or holiday at sundown. The candle burns for about 25 hours and it allowed to burn itself out. Whenever candles are left burning, please be sure to take safety precautions, such as placing the candle on a foil-lined metal baking tray in a place where it is not likely to be knocked over.
The Eternal One spoke to Moses, saying, "Phinehas, son of Eleazar son of Aaron the priest, has turned back My wrath from the Israelites by displaying among them his passion for Me, so that I did not wipe out the Israelite people in My passion." - Numbers 25:10-11