The Sacred Harp musical tradition evolved in the American South from a particular way of producing congregational sacred choral music. This form of music uses a special kind of musical notation called shaped notes, which represent each tone within the octave as a distinct shape in order to facilitate sight reading.
Modern music is very different from the forms employed in the Sacred Harp style of music. Historically, the roots of this music were the choral music and hymn-singing from church choirs and congregations, but it places more emphasis on a single song leader. Strong emphasis is placed on relative pitch and polyphony and the harmonies use open fifths, and parallel octaves and fifths not commonly heard in more modern choral usage.
There are two forms of this music that are common, 'fuguing tunes' and anthems. The fuguing tune is not the same as the classic fugue, but rather a more simple, though similar, form. Like the traditional fugue, the voices enter one at a time, coming together in the creation of a collective piece. Anthems tend to be longer songs, containing only one verse.
Sacred Harp singing is only a small portion of the shape note singing that evolved in the early 19th century. It was originally designed as a method to make sight reading and singing easier for novices, including children. People unfamiliar with traditional musical notation were attracted to the ease of reading the shaped notes. This musical tradition uses the old English form of only four shapes within an octave. Shape note systems lost popularity in the North where the more fashionable academic approach to harmony was taken, yet they entirely never disappeared in the South, where they remained a very popular tool for producing more ancient sacred choral music.
Sacred Harp music is a very old form of music writing, but new shape note music is being written all the time. Singers of Sacred Harp music are also creators in their own right, because the genre is evolving all the time as the music is performed. So this very old form is being remade new all the time.
It combines joy and inspiration with practiced technique in a unique spiritual art form.