The pianoforte, commonly known simply as the piano, is a keyboard instrument that produces sound by way of a series of taut metal strings that are struck with felt-covered hammers. The name derives from two Italian words, piano, meaning 'soft', and forte, meaning 'strong', or, in the context of music, 'loud', in reference to the mechanism for actuating the hammers, known as the action, allowing the performer to produce a wide dynamic range, with fine control over dynamics; this is in contrast to earlier keyboard instruments such as the harpsichord, clavichord and organ, which by and large had only crude methods for varying dynamics.
The piano first emerged in the early eighteenth century in the form of the fortepiano. This early form of the instrument had its strings stretched on a wooden frame, which meant that strings had to be kept under relatively low tension; this led to reduced sustain and a tone which many at the time found unpleasant. The invention, around the beginning of the nineteenth century of modern pianos with steel frames allowed the strings to be kept at much higher tension, allowing composers more versatility in writing for the instrument. Aside from certain unusual instruments, the design has remained more or less unchanged since then.
The piano comes in two principal varieties. The grand piano, the older and larger of the two, is a large instrument with the strings set out horizontally, starting behind the keyboard and stretching away from the performer. Its primary use is in concert halls, though smaller grand pianos are occasionally found in people's homes. Far more common as a home instrument is the more compact upright piano, in which the strings are arranged vertically in front of the performer.
The piano finds most of its use in Western classical music and jazz, though it is also often found in Western popular music. Another musical genre which is notable for using the piano almost exclusively is ragtime. Certain twentieth- and twenty-first-century Western classical composers have called for objects to be placed inside a piano, producing what is known as a prepared piano; a grand piano is usually used for this purpose.