So Who is this Holy Spirit?

Galatians 5:25, John 14-16—Most people have a decent understanding of who God is. The person of Jesus, His life, and ministry here on earth is well documented. Yet the person of the Holy Spirit is often the hidden member of the Trinity. To many, His work and role is a mystery. It’s impossible for us to stay in step with the Spirit if we don’t know the Spirit. So just who is this One that we are to stay in step with?