WHAT IS KADDISH?
Jewish tradition exhorts us to properly mourn the passing of a loved one, but also to set boundaries to our mourning. To not mourn at all, or to plunge into an abyss of grief and remain trapped on its bottom--both these extremes are detrimental, both to the living and to the soul of the departed. Mourning is a show of respect to the departed and to his/her place in our lives, as well as a crucial stage in the healing of those who experienced the loss. But the soul of the departed does not desire that those remaining in this world remain paralyzed by grief. Remarkably, the Mourner's Kaddish does not mention death, nor make any reference to the deceased. It is directed, instead, at the living and an Era of the Moshiach, when all illness and suffering will cease, and requests that this time be ushered in during our lifetime. (
See full article here).
There are also many interpretations as to why a minyan is needed to say Kaddish. The one I subscribe to is that we are a community, and no member of a community should be made to mourn alone. It is a mitzvah to simply be counted among a minyan so any Jew who wishes to say Kaddish can do so.
Kaddish is normally said daily during the first 30 days after the loss of a loved one (called
Shloshim) and thereafter on the anniversary of the date of death on the Jewish calendar (
Yahrzeit) .