Celestial Kingdom is the highest of the three "degrees of glory," according the doctrine of the Church of Jesus Christ of Latter-day Saints. The primary source of this doctrine is a vision recounted by Joseph Smith and Sidney Rigdon, at Hiram, Ohio, February 16, 1832, and recorded in Doctrine and Covenants, Section 76.
According to this doctrine, only those who attain the Celestial Kingdom will be united with their families in the eternities. Children who die before the age of eight all reach the Celestial Kingdom in the afterlife. Persons who reach maturity will only be judged by God to be worthy of the Celestial Kingdom if they have performed all required ordinances (baptism, endowment, and sealing), repented of their sins, and remained faithful to the end of their life.