The trio sonata was the most popular chamber music form during the baroque period. It consisted of two melody instruments accompanied by the “continuo” which was, in effect, a two-player bass and rhythm section.
The form developed during the 17th century and reached its full potential in the 4 sets by Arcangelo Corelli published in the 1680s and 90’s. The form was continued by all the great composers of the age and into the second half of the 18th century, when its place was taken over by the modern trio form. (See Chamber music)
The melody instruments were usually two violins, but not always. Handel’s opus 1 contains trio sonatas for various instruments including the flute and recorder - and there are many instances of wind and even keyboard supplying the melody.
Reference: “The Grove Concise Dictionary of Music”