Jesus will come at the end of time to judge all human beings. This is called the parousia, His second coming. It was foretold by the angels as He ascended: "This Jesus who is taken up from you to heaven, will come in the way in which you saw Him going into heaven" (Acts 1:11).
However, those who die before the parousia will be judged immediately at their deaths. This is known as the particular judgment. The Epistle to the Hebrews says (9:27): " It is appointed to men to die once, and after that comes the judgment". Then, "Each one will receive his pay, according to his works" (1 Cor 3:8).
There are three possible outcomes to the particular judgment. Those whose love for God has been perfected in this life are taken straight to heaven, where they enjoy endless happiness in the face to face vision of God. Those who die in God's love but still love Him imperfectly must be purifed in the intermediate state of purgatory. Those, however, who reject God's love by mortal sin and die without repenting are condemned to the everlasting torments of hell. The general judgment at the end of time simply solemnly confirms the particular judgments of each one, with the difference that then the body as well as the soul will receive what is due it. And all God's judgments will be revealed as most just.
Taken from The Basic Catholic Catechism
PART FOUR: The Apostle's Creed VI-VIII
Seventh Article: "From thence He shall come to judge the living and the dead"
By William G. Most. (c)Copyright 1990 by William G. Most