The Holy Ghost has a variety of roles including witnessing of the Father and His Son, revealing the truth, cleansing sins, and giving us comfort and peace.
Witnesses of Heavenly Father and Jesus Christ:
One of the most important roles of the Holy Ghost is to witness of Heavenly Father and Jesus Christ. This means that the Holy Ghost testifies to the truth of their existence.
Reveals the Truth:
The Holy Ghost reveals to us that which is true. For example, in the Book of Mormon there is a promise that we can know by the power of the Holy Ghost the truth of the words it contains, "And when ye shall receive these things, I would exhort you that ye would ask God, the Eternal Father, in the name of Christ, if these things are not true; and if ye shall ask with a sincere heart, with real intent, having faith in Christ, he will manifest the truth of it unto you, by the power of the Holy Ghost. And by the power of the Holy Ghost ye may know the truth of all things" (Moroni 10:4-5.) Also see, "How to Know the Truth"
Cleanses Our Sins:
The Holy Ghost sanctifies, or cleanses, those who have repented of their sins through baptism. This is also called the baptism of fire or to be born of the spirit.
Gives Comfort and Peace:
The Holy Ghost can also comforts and give us peace when we are in need, "But the Comforter, which is the Holy Ghost, whom the Father will send in my name, he shall teach you all things, and bring all things to your remembrance, whatsoever I have said unto you. Peace I leave with you, my peace I give unto you: not as the world giveth, give I unto you. Let not your heart be troubled, neither let it be afraid" (John 14:26-27.)
How You Feel the Holy Ghost:
A person may feel the influence of the Holy Ghost in many different ways. Continue reading with the article, "How Do You Feel the Holy Ghost?" to learn more.