In a duet, what does "primo" refer to?

In a duet, "primo" refers to the upper part or melody line that is typically played or sung by the first performer. This term is commonly used in piano duets, where one player takes the "primo" part, often encompassing the more prominent and leading melodic elements of the piece. The other performer, which is often referred to as "secondo," typically plays the accompaniment or harmonic support, which is usually the lower part. This distinction helps to align expectations for both players regarding their roles in the performance, making it essential for interpretation and communication between musicians in a duet setting.