A Hymn is a stylized poem or from the Greek a paeon, which, traditionally is sung in either in unison or parts, by a group or a congregation, in praise to a God or to a deity. The book of Psalms, in the Old Testament of the Hebrew and Christian texts, is an early example of the stylized poem, which was incorporated for group usage by the body of beleivers in both Christianity and Judaism. The hymn form of music has evolved over the intervening centuries to incorporate, other stylizations such as plainsong, other scriptural passages set in rythmical and tonal systems, such as canticles and metrical latin hymnody. Late additions to the hymn's historical development incorporate elements in "gospel" hymns from prevailing popular music genres, in order to maintain contact with the leading edge of the developments of other forms of music.