The piano is a musical instrument played by means of a keyboard. It is one of the most popular instruments in the world. Widely used in classical and jazz music for solo performances, ensemble use, chamber music and accompaniment, the piano is also very popular as an aid to composing and rehearsal. Although not portable and often expensive, the piano's versatility and ubiquity have made it one of the world's most familiar musical instruments.
The word piano is a shortened form of pianoforte, the Italian word for the instrument (which in turn derives from the previous terms "gravicembalo col piano e forte" and fortepiano). The musical terms "piano" and "forte" mean "quiet" and "loud," and in this context refers to the variations in volume of sound the instrument produces in response to a pianist's touch on the keys: the greater a key press's velocity, the greater the force of the hammer hitting the string(s), and the louder the note produced.
The piano is a crucial instrument in Western classical music, jazz, film, television, and most other complex western musical genres. A large number of composers are proficient pianists—and because the piano keyboard offers an easy means of complex melodic and harmonic interplay—the piano is often used as a tool for composition.