From the Catechism of the Catholic Church, Simplified
Returning to the Creator (1020)
In the funeral liturgy, the Church speaks with assurance to the dying: "Go forth, Christian soul from this world. May you return to your Creator who formed you from the dust of the earth. May you see your Redeemer face to face" (Prayer of Commendation).
Judged Immediately (1021-1022)
Death ends the time to accept or to reject Christ's grace. The New Testament speaks of a judgment immediately after death. The parable of the rich man and Lazarus, and Jesus' words to the good thief, speak of a final destiny of the soul which is different for each person.
Every man receives his eternal retribution immediately after death. He enters into Christ's blessedness (immediately or after a purification) or into everlasting damnation. "At the evening of life, we shall be judged on our love" (St. John of the Cross).
Going to Heaven (1023-1025)
Those who die in God's friendship and are perfectly purified will see God face to face. "The souls of the blessed have been, are, and will be in heaven before they take up their bodies again and before the general judgment. They see God face to face, without the mediation of any creature" (Pope Benedict XII).
This perfect life with the Father, Son, and Holy Spirit (and with all the saints and angels) is called "heaven." It is complete happiness and the fulfillment of the deepest human longings. Although retaining their own identity, the elect live "in Christ" (Phil 1:23). "Where Christ is, there is life, there is the kingdom" (St. Ambrose).
Doors Opened by Jesus (1026)
Jesus Christ has "opened heaven to us," giving us full possession of the fruits of his Redemption and making us partners in his heavenly glorification. Heaven is the community which is perfectly incorporated with him.
Images of Heaven (1027)
This communion with God is beyond all human understanding. The New Testament uses images to express heaven (wedding feast, wine of the kingdom, the Father's house, paradise). "No eye has seen, nor ear heard, nor the heart of man conceived what God has prepared for those who love him" (1 Cor 2:9).
Seeing God (1028-1029)
God can be seen only because he gives man the capacity to see him. This is the "beatific vision." "How great will your happiness be, to be allowed to see God and to delight in the joy of immortality" (St. Cyprian).
The blessed in heaven continue to fulfill God's will. With Christ they "reign forever and ever" (Rev 22:5).