What are the roles of the Holy Ghost?

What are the roles of the Holy Ghost?

https://www.lds.org/youth/learn/yw/godhead/roles?lang=eng

The Holy Ghost, a member of the Godhead, bears witness of Heavenly Father and Jesus Christ. He is the source of personal testimony and revelation. He can guide us in our decisions and protect us from physical and spiritual danger. He is known as the Comforter, and He can calm our fears and fill us with hope. Through His power, we are sanctified as we repent, receive saving ordinances, and keep our covenants. It is through the influence of the Holy Ghost that we receive knowledge of Heavenly Father and Jesus Christ and feel Their power, goodness, and love.

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