In the titles given to the Psalms (which are from the original composition), King David is credited with 73 of the 150 Psalms, Asaph wrote 12, the sons of Korah wrote 11, Solomon wrote 2, Moses wrote 1, Ethan wrote 1, and 50 Psalms are anonymous. (We cannot be fully certain of all these numbers, since the Hebrew word translated "of" can also mean "for." So a Psalm "of" David, for instance, could be a Psalm "for" David.)
Asaph was a priest who headed the service of music. The sons of Korah were a guild of singers and composers. Solomon is the son of David who followed David in the throne. Moses is the same Moses who led the Israelites out of Egypt. Ethan is a priest.
