Psalm 18 is a psalm of great majesty which uses hyperbolic and grand imagery to describe God. It begins with symbolic descriptions of God: his strength is shown by comparing him to a rock. His ability to protect is shown by being called a fortress.
It is a psalm in which the believer's life is compared to that of an embattled warrior and God is not only shown as a savior but as an all-powerful mighty savior who uses all of the universe at his power. There is a theophany in which God is shown with smoke-filled nostrils, almost like a volcano. All is power is shown in order to bring about deliverance for the believer; all of nature is used to reflect God and the heavens, the universe, and the earth tremble at God's greatness.
This is one of the first praise psalms which uses the idea of warfare, and which endeavors to link God's greatness with God's power to deliver his people.