A devotional song is a hymn which accompanies religious observances and rituals. Traditionally devotional music has been a part of christian music, Hindu music,  Buddhist music, Islamic  music .
 A devotional is a part of the prayer service proper and is not, in these contexts, ornamentation.In Eastern and Near-Eastern religions, devotionals can function as communion prayer and meditation. These are sung in particular rhythms which are sustained over a prolonged period to give practitioners a mystical experience. In Hindu music the genre arising out of the Bhakti movement  it takes forms like Bhajan, Kirtan and Aarti