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 G-d” (Hallelukah).