The instrument known for having keys and is often used in orchestras is the piano. The piano is a versatile keyboard instrument that produces sound when its keys are pressed, striking strings with hammers inside the body of the instrument. It has a wide range of musical capabilities and is frequently used in solo performances, chamber music, and orchestral settings. The piano can accompany various musical styles, from classical to jazz, and its rich harmonic possibilities make it a favorite for composers and performers alike.