Bartolomeo Cristofori (di Francesco)
From the Encyclopædia Britannica.

(b. May 4, 1655, Padua, Republic of Venice--d. Jan. 27, 1731, 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 this 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 around 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 instrument builder. (A three-keyboard harpsichord dated 1702, sometimes attributed to Cristofori and bearing the arms of Ferdinando, is preserved at the Stearns Collection at the University of Michigan.) Cristofori apparently invented the piano around 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 improved his piano to the point where, by 1726, he had arrived at all essentials of the modern piano action. His frames, being made of wood in the manner of a harpsichord, were not capable of withstanding the string tension that allowed later pianos their more powerful tone. Nevertheless, to judge by surviving examples (e.g., in Leipzig and New York City), his pianos were responsive and had a wide, dynamic range.

Cristofori's design was largely ignored in Italy, but it soon became known and adopted in Germany through articles in dictionaries of music.