Today is the “birthday” of The Church of Jesus Christ of Latter-day Saints (often referred to as the “Mormon” or LDS Church). One of our Articles of Faith states that “We believe in the same organization that existed in the Primitive Church.” When we talk of the organization of the Church in 1830, it’s actually more accurately described as a restoration of the Church that Jesus Christ organized in His day.
For a chronology of latter-day Church History, see here.
For more on the Restoration of the gospel and Church of Jesus Christ, see the many sections of information here: “The Restoration of Truth.”
For more on the prophet, Joseph Smith, through whom the Church was restored, visit here (unofficial site) or here (Church’s official site).