The book of Revelation is the one prophetic book of the New Testament with 22 chapters. It was written by the Apostle John, one of Jesus' disciples, who also wrote the Gospel of John and the three epistles of John - five New Testament books in all. Revelation was written as John was in exile for his faith on the island of Patmos about A.D. 95.
The book divides itself into three principal parts. First, an opening vision of Jesus and messages to the seven churches of the Roman province of Asia. Second, there follows most of the book, which is a description of the seven years of tribulation that will come upon the earth: seven seals, seven trumpets, and seven bowls - the pressure God is bringing on the earth to secure repentance among the peoples. It all draws to a close with the second coming of Jesus Christ - King of kings and Lord of lords (19:16). Third, the book then ends with a brief description of the judgment and the new heavens and new earth.
This marvelous book was written to encourage the suffering saints, persecuted by the Roman Empire. Evil will not win. God will! It has much encouragement for every subsequent generation, because the end of things has not yet come. But it will. We need to be prepared.