A set of associated strings on a multi-stringed instrument such as the mandolin, 12-string guitar, lute or harpsichord. A course is composed of two or more strings tuned in unison, octaves, fifths, or some combination, and the component strings of a course are frequently of a different gauge. The multiple strings cause a more full or rich tone upon being strummed or plucked, and in many cases create a small distribution of the sound over the duration of the strum due to the physical separation of the strings.