Trio sonata

A Trio sonata is a baroque music composition for three parts: two melodic lines (usually played by instruments like the violin and flute) and a continuo, which provides harmonic support, typically played by a keyboard or a bass instrument with chordal instruments like cello or bassoon. Despite the name "trio," the basso part is considered an accompaniment, so the music actually involves four players. This form emphasizes intricate interplay between the melody lines while providing a harmonic foundation, and it was popular in 17th and early 18th-century European music.