The instrument with 88 keys is the piano. This musical instrument is widely recognized for its striking versatility and expressive range. It features 52 white keys and 36 black keys, which allow musicians to produce a vast array of tones and dynamics. The piano is integral to numerous musical genres across the globe, from classical and jazz to pop and rock. It operates using hammers that strike strings when the keys are pressed, creating sound. Its design allows for both melodic and harmonic playing, making it a staple for composers, performers, and music enthusiasts alike.