A father brings his son into this world; a son can carry his father into the world to come. When a soul leaves this world and begins its journey upward, its children can assist it on its way. When a son brings more light and holiness into this world, the souls of his father or mother are lifted. Reciting Kaddish is a powerful tool of light for the children of the deceased.
The Kaddish is essentially a framework around the central words recited by the entire congregation: "May His Great Name be forever blessed." When the mourner recites the Kaddish and the congregation responds in unison with these words, a spark of light penetrates all worlds, and the soul of the deceased ascends.
Even if there is no child, another person can recite Kaddish, since we are all connected.
The children recite Kaddish daily for their deceased father and/or mother for eleven months after the death and then annually on the anniversary.
We pray three times a day: morning, afternoon, and evening. The Kaddish is recited at least once during each service.