A hymn is a type of song, and partially synonymous with devotional song, 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". A writer of hymns is known as a hymnist. The singing or composition of hymns is called hymnody. Collections of hymns are known as hymnals or hymn books. Hymns may or may not include instrumental accompaniment.

Although most familiar to speakers of English in the context of Christianity, hymns are also a fixture of other world religions, especially on the Indian subcontinent (stotras). Hymns also survive from antiquity, especially from Egyptian and Greek cultures. Some of the oldest surviving examples of notated music are hymns with Greek texts.