The piano is a musical instrument that is both a percussion and a string instrument. In the traditional Hornbostel-Sachs system of categorizing musical instruments, the piano is considered a type of chordophone, which is an instrument that produces sound by way of vibrating strings. The strings in a piano are stretched between two points, and when they vibrate, they produce sound. However, those vibrations are initiated by hammers hitting the strings rather than by plucking or by moving a bow across them. This method of playing makes the piano a percussion instrument, where instead of striking a drum, youre striking a string. Therefore, the piano is classified as a percussion instrument because it produces sound by striking the strings with hammers. In summary, the piano is a unique instrument that combines elements of both string and percussion instruments to produce its unique sound.