The Latter Day Saint movement (also called the LDS movement or LDS restorationist movement) is the collection of independent church groups that trace their origins to a Christian primitivist movement founded by Joseph Smith in the late 1820s. Collectively, these churches have over 15 million members. The vast majority of adherents belong to The Church of Jesus Christ of Latter-day Saints (LDS Church), with their predominant theology being Mormonism. The LDS Church self-identifies as Christian. A minority of Latter Day Saint adherents, such as members of the Community of Christ, believe in traditional Protestant theology, and have distanced themselves from some of the distinctive doctrines of Mormonism. Other groups include the Remnant Church of Jesus Christ of Latter Day Saints, which supports lineal succession of leadership from Smith's descendants, and the more controversial Fundamentalist Church of Jesus Christ of Latter-Day Saints, which defends the practice of polygamy.

The Church of Jesus Christ of Latter-day Saints (the LDS Church or, informally, the Mormon Church) is a Christian restorationist church that is considered by its followers to be the restoration of the original church founded by Jesus Christ. The church is headquartered in Salt Lake City, Utah, and has established congregations (called wards or branches) and built temples worldwide. According to the church, it has over 85,000 missionaries and a membership of over 15 million. It is ranked by the National Council of Churches as the fourth-largest Christian denomination in the United States. It is the largest denomination in the Latter Day Saint movement founded by Joseph Smith during the period of religious revival known as the Second Great Awakening.