For example, in the Bible in Isaiah 6, the story of Isaiah seeing the Lord sitting upon a throne is called a theophany.
According to the philosopher Philo, God is purely transcendent, so his interactions with the material world are through an expression of himself, his Logos, or Word. It was through this Word that God created the world.
Jewish inter-testamental tradition personifies this expression of God as a special angel who has the task of representing God to men. This angel is called the Angel of the Face, or the Angel of the Presence, or Metatron. He has the highest place in heaven next to God, and interceedes for Israel.
Christianity posits that God is a trinity; it also teaches that God became especially immanent through the Incarnation of Jesus Christ, who is at once fully God and fully human. The Feast of Theophany in the Eastern Orthodox Church on January 6 celebrates Jesus' baptism in the Jordan, at which time both Jesus' divinity and the the Trinity was made manifest by the appearance of Jesus, the Holy Spirit in the form of a dove, while the audible voice of the Father was heard.