The Baroque cello or violoncello is a bowed (and occasionally plucked) string instrument of the violin family. The cello often plays the bass part, both in chamber music such as string quartets and the orchestra’s string section, where the cello may be reinforced an octave lower by the double basses. Figured bass music of the Baroque-era typically assumes a cello, viola da gamba or bassoon as part of the basso continuo group alongside chordal instruments such as organ, harpsichord, lute or theorbo.

Baroque-era cellos differed from the modern instrument in several ways. The neck has a different form and angle, which matches the baroque bass-bar and stringing. Modern cellos have an endpin at the bottom to support the instrument (and transmit some of the sound through the floor), while Baroque cellos are held only by the calves of the player. Modern bows curve in and are held at the frog; Baroque bows curve out and are held closer to the bow’s point of balance.

Modern strings normally have a metal core, although some use a synthetic core; Baroque strings are made of gut, with the G and C strings wire-wound. Modern cellos often have finetuners connecting the strings to the tailpiece, which make it much easier to tune the instrument, but such pins are rendered ineffective by the flexibility of the gut strings used on Baroque cellos. Overall, the modern instrument has much higher string tension than the Baroque cello, resulting in a louder, more projecting tone, with fewer overtones.

Source: Wikipedia