The viol and violin families both consist of bowed string instruments with hourglass silhouettes, but the two differ in the number of strings (four for the violin family, usually six for the viols), the tuning of the strings, and details of their shapes (thicker ribs and sloping shoulders for the viols, several shapes of soundholes for viols versus S-shaped soundholes for violins, flat backs for viols versus arched backs for violins, as well as far more variety of outlines for viols than violins). Viols have frets on their fingerboards, a feature that endeared the viol to amateur players then and now. All sizes of viols are played upright either between the legs or resting on them, and the bow is held underhand, so that the stronger bow stroke is the up bow, unlike the violin, whose more powerful motion is the down bow. Beginning in the late fifteenth century, viol consorts played all manner of notated western European polyphony, culminating in the vast English viol consort repertory in the years around 1600. By the early eighteenth century, the bass viol had assumed the role of solo instrument, with the addition of a seventh string attributed by some to the French bass viol virtuoso Sainte-Colombe (died 1691–1701).

This bass viol originally had six strings, with a seventh added later. It bears an erroneous label attributing it to Matthias Humel, Nuremberg, 1701.