For the director of music, a psalm of David.
This psalm is a psalm of praise for victories granted to the king. This is considered a Royal Psalm and thus there is a Messianic implication to it. In this likeness it is linked with Psalm 20. However Psalm 20 has the people’s prayer within it (liturgical) and Psalm 21 is just the king’s prayer.
In verses 1 – 7 is a praise to God for the victory he has given to the king.
In verses 8-12 the people hail the future victories of the triumphant king. verse 8 announces the theme, and verses. 9-11 develops the theme. verse 12 summarizes the whole psalm: “Be exalted, 0 Lord, in your strength; we will sing and praise your might”
This psalm reminds us all of God’s great power and put a new fear of God in us.