The Talmud (P’sachim 117a) states that there are ten types of songs/expressions in the Book of Psalms: 1) conducting (nitzuach), 2) melody (nigun), 3) musical accompaniment (mizmor), 4) song (shir), 5) praise (hallel), 6) prayer (t’filah), 7) blessing (brachah), 8) thanksgiving (hodaah), 9) praises (ashrei), and 10) “Praise God” (hallelukah).