The guitar originally had four courses of strings, three double, the top course single, that ran from a violin-like pegbox to a tension bridge glued to the soundboard, or belly; the bridge thus sustained the direct pull of the strings. In the belly was a circular sound hole, often ornamented with a carved wooden rose. The 16th-century guitar was tuned c–f–a–d¢, the tuning of the centre four courses of the lute and of the vihuela.

From the 16th to the 19th century several changes occurred in the instrument. A fifth course of strings was added before 1600; by the late 18th century a sixth course was added. Before 1800 the double courses were replaced by single strings tuned E–A–d–g–b–e¢, still the standard tuning.

PB