A hymn is a type of song, usually religious, specifically written for the purpose of adoration or prayer, and typically addressed to a deity or deities, or to a prominent figure or personification. The word hymn derives from Greek ὕμνος (hymnos), which means "a song of praise". The singing of hymns is called hymnody. Collections of hymns are known as hymnals or hymn books. Hymns may or may not include instrumental accompaniment.