A Yahrzeit is the anniversary of a death of a loved one. Traditionally, the yahrzeit is observed by lighting a special candle that burns for 24 hours. The candle is lit on the anniversary of the Hebrew date of that person’s death, as well as on certain holidays throughout the year. Traditionally Yahrzeit candles are lit for parents, spouses, siblings, and children, but there is no reason one could not light a Yahrzeit candle to honor the anniversary of the death of someone who doesn’t fall into one of these categories (i.e. a friend, grandparent, boyfriend/girlfriend, etc.). Although Jewish religious law does not require lighting Yahrzeit candles, the tradition has become an important part of Jewish life and mourning.
Yahrzeit Calendar (Calendar graciously borrowed from Hebcal)