The Holy Ghost is the third member of the Godhead. He is a personage of Spirit, not having a body of flesh and bones. This means that He can dwell within each one of us. I like to portray this as the influence of the sun. There is only one sun, but it's warmth and light can be felt by all.
His primary purposes are to bear witness of the Father and the Son, reveal the truth of all things, and to sanctify those who have repented and become baptized. There are many 'voices' that compete for our attention in this busy world and they can easily drown out spiritual impressions if we're not careful. The voice of the spirit is distinct in the way that it:
Listening to the quiet whisperings of the spirit comes in a variety of ways including experiencing feelings, thoughts, and impressions. Some of these feelings include love, joy, peace, patience, gentleness, faith, and hope. Who wouldn't want to feel any of those feelings? We need to strive constantly to listen to these promptings and valiantly and courageously act on them. Doing so will give us better direction in our lives, all of the aforementioned feelings, and the constant companionship of one of the members of the Godhead. I testify that having the Holy Spirit as our companion is vital in everything we do.