Who - The sons of Korah to the LORD.
What - A pilgrimage psalm. The psalmist is writing of the joy to go to Jerusalem and worship at the temple.
When - Unstated
Where - Unstated
Why - The psalmist is expressing the joy of coming to the temple to worship. As this is a choir song it is also a song to be sung to help all worshipers find delight and joy in coming to worship the LORD. It reads as a song to be sung on the way to Jerusalem.
