A piano trio is a musical ensemble consisting of a piano, a string instrument, and a percussion instrument. The two most common instruments used in a piano trio are the violin and the cello. The term 'PEDALS' refers to the foot PEDALS on a piano, which are used to control the volume and sustain of the notes. The term 'LEGS' refers to the LEGS of the piano, which are used to support the instrument and keep it in place.