Bartolomeo Cristofori, in full Bartolomeo di Francesco Cristofori, (born May 4, 1655, Padua, Republic of Venice [Italy]—died January 27, 1732, Florence), Italian harpsichord maker generally credited with the invention of the piano, called in his time gravicembalo col piano e forte, or “harpsichord that plays soft and loud.” The name refers to the piano’s ability to change loudness according to the amount of pressure on the keys, a quality foreign to the harpsichord. Cristofori achieved that effect by replacing the plucking mechanism of the harpsichord with a hammer action capable of striking the strings with greater or lesser force.

Little is known of Cristofori’s life, and his invention was not well known in his lifetime. He moved from Padua to Florence about 1690 at the request of Prince Ferdinando de’Medici, an accomplished harpsichordist, a move suggesting that Cristofori had already established a reputation as a skilled keyboard instrument builder.

Cristofori apparently invented the piano about 1709, and, according to contemporary sources, four of his pianos existed in 1711. In 1713 Ferdinando died, and Cristofori remained in the service of the grand duke, Cosimo III, later (1716) becoming responsible for the care of an instrument collection assembled by Ferdinando; of 84 instruments, 7 were harpsichords or spinets of Cristofori’s manufacture.

Cristofori was an artful inventor, creating such a sophisticated action for his pianos that, at the instrument’s inception, he solved many of the technical problems that continued to puzzle other piano designers for the next seventy-five years of its evolution.

Cristofori’s ingenious innovations included an “escapement” mechanism that enabled the hammer to fall away from the string instantly after striking it, so as not to dampen the string, and allowing the string to be struck harder than on a clavichord; a “check” that kept the fast-moving hammer from bouncing back to re-hit the string; a dampening mechanism on a jack to silence the string when not in use; isolating the soundboard from the tension-bearing parts of the case, so that it could vibrate more freely; and employing thicker strings at higher tensions than on a harpsichord.

Subsequent technological developments in the piano were often mere "re-inventions" of Cristofori's work; in the early years, there were perhaps as many regressions as advances.

According to Britannica – Wikipedia - metmuseum.org