Traditional Judaism delineates a series of steps, beginning with the moment of death, as follows:
Aninut - from death to burial.
Shiva – the first seven days of mourning; the day of burial is day one.
Sheloshim – the first thirty days from the day of burial, including the shivah; the complete mourning period for all except for a parent.
Yud-bet chodesh – the “year of mourning”, actually the twelve Hebrew months following the day of death, the mourning period for a parent.
Yahrzeit – the anniversary date of the death, according to the Jewish calendar.
What is the meaning of Aninut?
Aninut, a Hebrew word meaning "deep sorrow," is a legal category of mourning used to designate the period from death to burial. An individual who has lost a loved one is referred as an Onenduring this time.
Are there any special requirements of an Onen?
Quite the contrary. Jewish tradition recognizes that the enormous pain and shock of loss must be respected. Accordingly, an onen is freed from the responsibility of performing any positive Mitzvot(except observing the Shabbat), such as reciting the Shema or putting on Tefilin. In addition, even close friends are instructed not to express condolence "when his deceased lies before him" (Pirke Avot IV:23) but rather to wait until after the interment. That is why it is only as the family leaves the cemetery that friends are first allowed, by tradition, to utter the traditional words of comfort: "May the Almighty comfort you among all the other mourners of Zion and Jerusalem."
What is Avelut?
Avelut, a Hebrew word meaning "lamenting," refers to the mourning period following interment. A mourner during this period is called an avel. Avelut, which follows aninut, encompasses the mourning customs of shivah, sheloshim, and, when a parent has died, the entire twelve-month mourning period.