^^ The book of mormon was revealed by Joseph Smith, in the 1830's, who mormons hold was a prophet. It's a collection of ancient american writings, by people in america, starting with Lehi, who led his family out of Jerusalem to the americas about 600 b.c. the Highlight of the book is when Jesus visits america shortly after his resurrection. (In the new testament, he tells his disciples he has other sheep to visit).
There's no historical record of the book before Joseph Smith, so either he was a prophet of god, or the entire book is false. It's basically a continuation of Christianity, that holds that the old testament, new testament, and book of mormon are all 3 testaments of christ, and are all 3 the word of god. Like the reformed churches started in the 1500's (My date MAY be wrong) (protestant churches), Mormons are a restored church, they (we) contend that Smith was visited by God, and by Jesus, and was told how to restore the church back to it's original form (how it was at Jesus's death)... Official church name is the Church of Jesus Christ of Latter Day Saints. Lemme know if you wanna know more, or you could check out www.mormons.org (official church website) Peace~