Pressing a key on the piano's keyboard causes a padded (often with felt) hammer to strike steelstrings. The hammers rebound, and the strings continue to vibrate at their resonant frequency. These vibrations are transmitted through a bridge to a sounding board that more efficiently couples the acoustic energy to the air. The sound would otherwise be no louder than that directly produced by the strings. When the key is released, a damper stops the string's vibration and the sound. In the Hornbostel-Sachs system of instrument classification, pianos are considered chordophones.
The word piano is a shortened form of pianoforte (PF), the Italian word for the instrument (which in turn derives from the previous terms gravicembalo col piano e forte and fortepiano). The Italian musical terms piano and forte indicate "soft" and "strong" respectively, in this context referring to the variations in sound volume the instrument produces 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.
Pleyel et Cie ("Pleyel and Company") is a French piano manufacturing firm founded by the composer Ignace Pleyel in 1807. In 1815, he was joined by his son, Camille, as a business partner. The firm provided pianos to Frédéric Chopin, and also ran a concert hall, the Salle Pleyel, where Chopin performed his first — and last — Paris concerts. Pleyel's major contribution to piano development was the first use of a metal frame in a piano. Pleyel pianos were the choice of composers such as Debussy, Saint-Saëns, Ravel, de Falla, and Stravinsky.