Summary: The dead appear before God, and all who are not written in the Book of Life- that is, who have not during one of history’s eras put their trust in God- are consigned to the lake of fire.
"I cannot preach on hell unless I preach with tears." - D.L. Moody
"Then death and hades were thrown into the lake of fire. The lake of fire is the second death" (Rev. 20:14)
The thousand-year-reign. This is the only mention in the Bible of a thousand-year period during which Christ rules on our present earth. Yet many of the themes seen in this puzzling chapter are developed quite fully in the Old Testament and in Christ’s own eschatological teaching. One scenario, which may not be correct, but which is most fascinating, explains the chapter in this way.
After the armies of earth are crushed at Christ’s return, the surviving population experiences the judgement described in Matthew 24 (quickview) . Many who enter the kingdom Christ will rule are thus unconverted individuals; if you will, Germans, but not Nazis. Christians, members of the body of Christ, have already met Christ in the air, as 1 Thessalonians 4 (quickview)  describes. The martyrs who experience the "first resurrection" are Old Testament saints or believers of the Tribulation era, as Daniel 12:4 (quickview)  indicated. These reign with Christ on earth for the thousand years, fulfilling the prophet’s predictions of an era of peace under the Messiah.
Despite the ideal environment established by Christ in the Millennium, when Satan is released at the end of the era he finds willing followers among the descendants of the survivors, eager to rebel against the Lord. This final rebellion is quickly put down, Satan is assigned to the lake of fire, and at this point the universe itself dissolves, as described by Isaiah and in 2 Peter 3 (quickview) .
Now final judgement takes place. The dead appear before God, and all who are not written in the Book of Life- that is, who have not during one of history’s eras put their trust in God- are consigned to the lake of fire.
One thing fascinates me about this interpretation of Revelation 20 (quickview)  and the many Old Testament and New Testament passages integrated with it. When God warned Adam in the Garden of Eden not to disobey, He said, "When you eat of it you will surely die" (Gen. 2:17). When Adam sinned death struck: first a spiritual death, and out of that biological deterioration. Now matter what man accomplishes in the physical universe, humanity remains spiritually dead, the grip of sin tragic and unbreakable.
One way to look at sacred history is to see it as a demonstration of this fact, and the utter necessity of salvation. Human beings can and do blame crime and corruption on environment, on society, on Satan’s influence, and on a host of other factors beyond individual control. But the fact remains that it is because of sin and spiritual death that pain and evil stalk us still.
God first gave man utter freedom and the world became so evil the race had to be destroyed in the Genesis Flood (Gen. 6-8). Then God instituted human government by making man responsible to correct evils (9:6). And ancient empires emerged, whose rulers’ pride and greed was expressed in terrible wars and torture. Then God chose a single family, the Jewish race, and covenanted to be their God. Even though He gave them a law that showed how to love Him and one’s fellow man, Israel rebelled again and again, turning aside to idolatry. So God sent a Saviour, and proclaimed a Gospel of forgiveness and transformation for all. And the world ignored the invitation, preferring the pursuit of sinful desires. So at the last Christ institutes a kingdom where righteousness is enforced: a golden age of peace and plenty, with Satan’s influence removed. Even then, when Satan is released, mankind gladly throws off the bondage of goodness to rebel yet again against God. In this all the awfulness of sin is finally, fully, revealed. And man apart from God’s redeeming grace is shown to be a sinner indeed.