"...death primarily involves the dissolution of the entire psychophysical personality of man. The soul survives and subsists separated from the body, while the body is subjected to gradual decomposition according to the words of the Lord God, pronounced after the sin committed by man at the beginning of his earthly history: "You are dust and to dust you shall return"...By His salvific work, the only-begotten Son liberates man from sin and death. First of all He blots out from human history the dominion of sin, which took root under the influence of the evil spirit beginning with original sin, and then He gives man the possibility of living in sanctifying grace. In the wake of His victory over sin, He also takes away the dominion of death, by His resurrection beginning the process of the future resurrection of the body. Both are essential conditions of "eternal life," that is, of man's definitive happiness in union with God."
Above from section 15 of John Paul II's Apostolic Letter Salvifici Doloris,
Purgatory is a condition of existence
where already saved souls are cleansed of the temporal effects of sin before they are allowed to see the holy face of Almighty God.
11 February 1984.