THE HOLY SPIRIT The Holy Spirit is the third person in the Trinity. He is God, because he is in the Godhead. The Holy Spirit is a power, it talks about that in Acts 1: 8. But ye shall receive power, after that the Holy Ghost is come on you. The Holy Spirit dwells in us teaching us, inspiring us, and giving us power. The Holy Spirit is equal with God and the Son.
If you have the Holy Spirit in you it is the same as having Christ in you (Romans 8: 9-12). The Holy Spirit is a comforter it says in John 14: 16, 17. If you obey me; and I will ask the Father and he will give you another Comforter, and he will never leave you. He is the Holy Spirit, the Spirit who leads into all truth. The world at large cannot receive him, for it isn't looking for him and doesn't recognize him. But you do, for he lives with you now and some day shall be in you, The Holy Spirit does many different things and all through out the Bible it says the different things that the Holy Spirit does.
The Holy Spirit teaches us, He brings things to our memory, He bears witness, and He convinces us of our sin. He also speaks through us to other people, or speaks threw another person to us, such as a minister or a close friend. The Holy Spirit can often inspire us to do things like talk to somebody or read a certain scripture. So basically what the Holy Spirit does is he empowers us.