Mormons believe that: Moroni first appeared as a resurrected being (or angel) to Joseph Smith, Jr in 1827; Moroni delivered gold plates to Joseph; the plates are the record of Moroni's people, ancient Americans known as Nephites and Lamanites; Moroni's father, Mormon (also a prophet), compiled and abridged the plates from the many records of their people over the centuries; and Joseph translated one-third of the plates into a book called The Book of Mormon after which Joseph gave the plates back to Moroni.
The Book of Moroni is also the last book at the end of the Book of Mormon.
See also Moroni, Utah