This is a big question on which many books have been written!
Let me start first by saying that while this site has been established by Sydney Anglican Media department, it is not designed to be an Anglican site. We are more interested in presenting what the bible says about God, Jesus and humanity than what are the defined Anglican doctrines (though there will be quite a bit of overlap).
The Holy Spirit is the third person of the Godhead - the Father, the Son and the Holy Spirit. Most of what Jesus taught about the Holy Spirit can be found in John’s gospel, chapters 14-16.
Here the Holy Spirit is seen as the one who will continue the ministry of Jesus on his behalf in the world. Just as Jesus has been living amongst them and teaching them about God, so the Holy Spirit will live in them and continue to teach them about God. In particular the Holy Spirit is to:
1. Convict the world of sin, righteousness and judgement. That is the work of the Holy Spirit is to show people that they need to be forgiven by God. He has aan integral role in the salvation of sinners.
2. Guide and enable the disciples and others to understand the truth about God. That is the Holy Spirit continues to teach us about God, Jesus and ourselves and what God has done and is doing in the world. He has an integral role in the growth and maturing of Christians.
The Spirit’s principle method of activity is to help us understand God’s word and apply it to our personal circumstances. In several places God’s word is (Bible) is described as a sharp sword (Heb 4:12, Eph 6:17, Rev 1:16). In Eph 6:17 in particular, God’s word is described as “the Sword of the Spirit” and as such is the Spirit’s principle weapon. This makes sense of course because people only become convicted of their need to turn to God as they hear about God in his word. And Christians only grow in their faith and commitment as they study God’s word.
The Spirit is also the means by which God gifts his people for various activities. There has been a great deal said about Spiritual gifts but the essential aspect of them is that they are given out for the benefit of God people and growing the church. So those with the gift of evangelism are particularly good at telling people about God out of his word. And those with the gift of teching are particularly good at explaining God’s word to others. In other words, the spiritual gifts enable us to be a part of the work that God does in the world through His Spirit.
This is only a very short description of who the Holy Spirit is and glosses over many of the details, however it does five you and idea of who he is.