The Book of Mormon is the name of a book, or division, in the larger Book of Mormon. This "inner" book has nine chapters. According to the text, the first seven chapters were written by the prophet Mormon and the last two by his son Moroni. These men were given a sacred charge to observe the destruction of their people for their wickedness and failure to repent; and to record their observations on metal plates which would be hidden until the Lord would reveal them to the world at a future time.
The book thus explains the alleged provenance of the Book of Mormon as an ancient record, mostly of the Nephites, compiled by Mormon and Moroni on Golden Plates.
Important Teachings Given by the Prophet Mormon
Yea, behold, I write unto all the ends of the earth; yea, unto you, twelve tribes of Israel, who shall be judged according to your works by the twelve whom Jesus chose to be his disciples in the land of Jerusalem. And I write also unto the remnant of this people,... that ye may know that ye must all stand before the judgment–seat of Christ, yea, every soul who belongs to the whole human family of Adam; and ye must stand to be judged of your works, whether they be good or evil; And also that ye may believe the gospel of Jesus Christ, which ye shall have among you; and also that the Jews, the covenant people of the Lord, shall have other witness besides him whom they saw and heard, that Jesus, whom they slew, was the very Christ and the very God. And I would that I could persuade all ye ends of the earth to repent and prepare to stand before the judgment–seat of Christ. (Mormon 3:18 - 22)
Now these things are ... to be hid up unto the Lord that they may come forth in his own due time. And this is the commandment which I have received; and behold, they shall come forth according to the commandment of the Lord, when he shall see fit, in his wisdom. And behold, they shall go unto the unbelieving of the Jews; and for this intent shall they go—that they may be persuaded that Jesus is the Christ, the Son of the living God; that the Father may bring about, through his most Beloved, his great and eternal purpose, in restoring the Jews, or all the house of Israel, to the land of their inheritance, which the Lord their God hath given them, unto the fulfilling of his covenant; (Mormon 5:12 - 14)