ornamentation
The practice of decorating a melody with additional notes that embellish the original line
In Depth
Ornamentation encompasses all the small-scale decorative additions to a melody: trills, mordents, turns, grace notes, appoggiaturas, slides, and free embellishment. In Baroque music, performers were expected to add ornaments that the composer had not written. In Classical music, ornaments were increasingly specified in the score. The correct style of ornamentation varies dramatically between periods, national traditions, and individual composers. Performing with historically appropriate ornamentation is a specialised skill.
Baroque ornamentation was so elaborate that CPE Bach, Quantz, and Tartini each wrote entire treatises devoted solely to the art of embellishing a melodic line.