The piano (an abbreviation of pianoforte) is a musical instrument played using a keyboard. It is widely employed in classical and jazz music for solo and ensemble performances, accompaniment, and for composing and rehearsal. Although the piano is not portable and often expensive, its versatility and ubiquity have made it one of the world's most familiar musical instruments.
An acoustic piano usually has a protective wooden case surrounding the soundboard and metal strings, and a row of 88 black and white keys (52 white, 36 black). The strings are sounded when the keys are pressed, and silenced when the keys are released. The note can be sustained, even when the keys are released, by the use of pedals.
Pressing a key on the piano's keyboard causes a padded (often with felt) hammer to strike strings. The hammer rebounds, and the strings continue to vibrate at their resonant frequency. These vibrations are transmitted through a bridge to a soundboard that amplifies by more efficiently coupling the acoustic energy to the air. When the key is released, a damper stops the strings' vibration, ending the sound. Although an acoustic piano has strings, it is usually classified as a percussion instrument because the strings are struck rather than plucked (as with a harpsichord or spinet); in the Hornbostel-Sachs system of instrument classification, pianos are considered chordophones. With technological advances, electric, electronic, and digital pianos have also been developed.
The word piano is a shortened form of pianoforte, the Italian term for the instrument, which in turn derives from gravicembalo col piano e forte and fortepiano. The Italian musical terms piano and forte indicate "soft" and "loud" respectively, in this context referring to the variations in volume produced in response to a pianist's touch on the keys: the greater the velocity of a key press, the greater the force of the hammer hitting the strings, and the louder the sound of the note produced.
The pipe organ is a musical instrument that produces sound by driving pressurized air (called wind) through pipes selected via a keyboard. Because each organ pipe produces a single pitch, the pipes are provided in sets called ranks, each of which has a common timbre and volume throughout the keyboard compass. Most organs have multiple ranks of pipes of differing timbre, pitch and loudness that the player can employ singly or in combination through the use of controls called stops.
A pipe organ has one or more keyboards (called manuals) played by the hands, and a pedalboard played by the feet, each of which has its own group of stops. The keyboard(s), pedalboard, and stops are housed in the organ's console. The organ's continuous supply of wind allows it to sustain notes for as long as the corresponding keys are depressed, unlike the piano and harpsichord whose sound begins to decay immediately after attack. The smallest portable pipe organs may have only one or two dozen pipes and one manual; the largest may have over 20,000 pipes and seven manuals.
The origins of the pipe organ can be traced back to the water organ in Ancient Greece in the 3rd century BC, in which the wind supply was created with water pressure. By the 6th or 7th century AD, bellows were used to supply organs with wind. Beginning in the 12th century, the organ began to evolve into a complex instrument capable of producing different timbres. A pipe organ with "great leaden pipes" was sent to the West by the Byzantine emperor Constantine V as a gift to Pepin the Short King of the Franks in 757. Pepin's son Charlemagne requested a similar organ for his chapel in Aachen in 812, beginning its establishment in Western church music. By the 17th century, most of the sounds available on the modern classical organ had been developed. From that time, the pipe organ was the most complex man-made device, a distinction it retained until it was displaced by the telephone exchange in the late 19th century.
Pipe organs are installed in churches, synagogues, concert halls, and other public buildings and are used for the performance of classical music, sacred music, secular music and popular music. In the early 20th century, pipe organs were installed in theaters to accompany films during the silent movie era, in municipal auditoria, where orchestral transcriptions were popular, and in the homes of the wealthy, equipped with player mechanisms. The beginning of the 21st century has seen a resurgence in installations in concert halls. The organ boasts a substantial repertoire, which spans over 500 years.