The denominations in the Latter Day Saint movement are sometimes collectively referred to as Mormonism. Mormon is an informal term used especially when referring to the largest Latter Day Saint denomination, the Church of Jesus Christ of Latter-day Saints (LDS Church), and other offshoots in the movement. Groups opposed to the use of the term Mormon such as the LDS Church consider it to be connected to the polygamy once practiced by the Utah church,^[1][2] or to pejoratives used against early adherents of the movement.^[3][4]

The Latter Day Saint movement includes:

• The original church within this movement, founded in April 1830 in New York by Joseph Smith, was the Church of Christ. It was later named the "Church of the Latter Day Saints". It was renamed the "Church of Jesus Christ of Latter Day Saints" in 1838 (stylized as the "Church of Jesus Christ of Latter-day Saints" in the United Kingdom),^[5] which remained its official name until Smith's death in 1844. This organization subsequently splintered into several different denominations, each of which claims to be the legitimate continuation of this original church. Most of these dispute the right of other denominations within the movement to claim this distinction.
• The largest denomination within the contemporary movement is the LDS Church, with approximately 17 million members.^[6] It is headquartered in Salt Lake City, Utah, and uses the term Latter-day Saints to describe itself and its members (note the hyphenation and variation in capitalization usage).
• The second-largest denomination is the Community of Christ (it was first named the "Reorganized Church of Jesus Christ of Latter Day Saints", which lasted from 1872 to 2001). This is a Missouri-based, 250,000-member denomination. Although members of this church have traditionally been called Latter Day Saints (without the hyphen), the Community of Christ has more recently stated that it rejects the use of the term Saints as a designation for its members in any official reference or publication.^[7]
• The largest groups of Mormon fundamentalism include the Fundamentalist Church of Jesus Christ of Latter Day Saints (FLDS), Centennial Park Group (The Work), Apostolic United Brethren (AUB or Allred Group), and Latter Day Church of Christ (DCCS or Kingston Group).^[8]
• Other denominations within the movement either formed around various would-be successors to Smith, or else broke from denominations that did. These, together with the two denominations listed above, are detailed in the table of denominations within the Latter Day Saint movement, below.

Although a few small factions broke with Smith's organization during his lifetime, he retained the allegiance of the vast majority of Latter Day Saints until his death in June 1844. Following Smith's death, the movement underwent a leadership crisis which led to a schism within the church. The largest group followed Brigham Young and settled in what became the Utah Territory and is now the Utah-based LDS Church. The second-largest faction, Community of Christ, coalesced around Joseph Smith III, eldest son of Joseph Smith. Other would-be leaders included the senior surviving member of the First Presidency, Sidney Rigdon; the newly baptized James Strang from Wisconsin; and Alpheus Cutler, one of the Council of Fifty. Each of these men still retains a following as of 2014—however tiny it may be in some cases—and all of their organizations have undergone further schisms.^[9][10][11] Other claimants, such as Granville Hedrick, William Bickerton, and Charles B. Thompson, later emerged to start still other factions, some of which have further subdivided.

Given the large number of Latter Day Saint churches and their differing backgrounds, categorizing them can be difficult. In the field of Mormon studies, terms such as Rocky Mountain Saints are sometimes used for those denominations headquartered in the American West and Prairie Saints for those denominations that formed in and around Nauvoo, Illinois; Voree, Wisconsin; Independence, Missouri; and other locations in the Midwest and East. These terms do not necessarily relate the current geographical locations of all denominations within those two groupings, but rather the original location of their respective parent organizations, which may be seen in the table below.

Another method uses provenance: for instance, all denominations that ultimately trace their history back to the LDS Church based in Utah, are organized as one factional group. Divergent Paths of the Restoration—a reference work on this subject—follows this approach.^[9]

In such studies, and in general Latter Day Saint parlance, the -ite-suffixed terms Josephite and Brighamite have been used for the Missouri-based Community of Christ and the Utah-based LDS Church, respectively; these terms have sometimes been used to distinguish groups of denominations as well. Those denominations within each group share a common ancestry and basic beliefs that are different from groups sharing other provenances. The present article, in a similar fashion, distinguishes among groups of denominations by use of commonly understood names such as Mormon fundamentalist or else by short descriptions that often reference a founder of the first church within a factional group–for example, Joseph Smith III in reference to Community of Christ as well as various churches and factions that trace their origin to it.