What is the Particular Judgment?
Everyone who has died or will die before the Second Coming of Christ is judged immediately at the time of his or her death. This is the Particular Judgment.
The New Testament speaks of the judgment mainly from the perspective of a final meeting with Christ when he comes again. But we also find in many places of the Sacred Scripture references to the retribution immediately
after each person's death as a consequence of his or her faith and deeds. We know with the certainty of faith that each person, at death, receives—in his or her immortal soul—an eternal retribution in a Particular Judgment. He or she immediately refers his or her life to Christ, going to one of three states: through a period of purification, directly to his definitive state in Heaven, or to eternal condemnation. (Cf. CCC 1051)
The Particular Judgment is an act by which God makes the soul understand clearly the state it is in. This illumination will lead directly either to the soul's union with God or its rejection of him. The General Judgment at the end of the world does not alter the results of the Particular Judgment in any way. The Sacrament of Penance, in which we ask forgiveness for our sins, in effect anticipates our Particular Judgment and aids us to avoid the eternal consequences of our transgressions. (Cf. CCC 1022,1470)
-The Didache Bible