Question

During the baroque, composers would often write an accompaniment for an ensemble that was partially improvised by the player. usually this part was played by the harpsichord, organ, or lute. the performers could add ornamentation and alter the parts as they saw fit depending on the situation. what was this part called?

Answer 1

This part is called "basso continuo" wherein an accompaniment from an original composition  of playing bass notes are often improvised to a form they saw that fits the mood. These accompaniments are usually organ, lute or hapsichord depending on the type of concerto they are performing.