The highest-ranking governing body in The Church of Jesus Christ of Latter-day Saints is the First Presidency, consisting of the president and his two counselors, or advisers. This three-man body supervises the work of the entire Church in all matters of policy, organization and administration.
The second-highest presiding body in Church government is the Quorum of the Twelve Apostles. Along with the First Presidency, members of the Quorum of the Twelve Apostles are special witness of Christ. The Quorum of the Twelve Apostles serves under the direction of the First Presidency and has heavy administrative responsibilities to oversee the orderly progress and development of the Church throughout the world. Members of the First Presidency and Quorum of the Twelve Apostles are regarded by Latter-day Saints as prophets who seek and receive divine revelation and inspiration to guide the Church.
The appointment of a new president of the Church happens in an orderly way. When the president of the Church passes away, the following events take place:
1. The First Presidency is automatically dissolved.
2. The two counselors in the First Presidency revert to their places of seniority in the Quorum of the Twelve Apostles. Seniority is determined by the date on which a person was ordained to the Twelve, not by age.
3. The Quorum of the Twelve Apostles, now numbering 14 and headed by the senior Apostle, assumes Church leadership.
4. As a quorum, they consider when the First Presidency should be reorganized.
5. After unanimous decision, the senior Apostle is ordained as the new president of the Church by the laying on of hands by the members of the Quorum of the Twelve Apostles. He then chooses two counselors and the three of them become the new First Presidency.
6. Following the reorganization of the First Presidency, the Apostle who has served the second longest is sustained as the president of the Quorum of the Twelve. When the second-longest-serving Apostle has also been called into the First Presidency as a counselor, the third-longest-serving Apostle becomes Acting President of the Twelve.
Since the Church was formally organized on April 6, 1830, there have been 17 presidents, including President Russell M. Nelson.