A witness is someone who gives a statement or evidence based on personal knowledge, or in other words, bears a testimony. The statement, testimony, or evidence is itself also a witness. 
- The Lord taught early Church leaders that “in the mouth of two or three witnesses shall every word be established” (Doctrine and Covenants 6:28; see also Matthew 18:16). Most of the important events in the Restoration of the Church followed the pattern of having multiple witnesses testify of their truthfulness. Some examples include:
- The Three Witnesses to the Book of Mormon testified that an angel showed them the gold plates and that the record on the plates, which became the Book of Mormon, was translated by the gift and power of God.
- The Eight Witnesses testified that Joseph Smith showed them the gold plates and that they were able to touch them and examine the engravings on them.
- Joseph Smith and Oliver Cowdery were present at and testified of the restoration of the priesthood and priesthood keys.
The role of witness belongs to members of the Church, who are all encouraged to “stand as witnesses of God at all times and in all things, and in all places” (Mosiah 18:8–9); who witness unto the Father when they partake of the sacrament that they will keep the commandments and always remember Jesus; who bear testimony of the tender mercies of God, His answers to their prayers, and their healings through His priesthood power, etc. Members of the Church also act as witnesses for ordinances and covenants.
Additionally, the Apostles are special witnesses of Jesus Christ. “They testify to all people of the reality of Jesus Christ, the truthfulness of His gospel, and the importance of His Atonement to all people.” The Seventy are called to be especial witnesses unto the Gentiles. (See Doctrine and Covenants 107:23, 25.)