Short answers, pulled from the story.
Bartolomeo Cristofori invented the fortepiano, and the first reliable record of his instrument appears in a Medici family inventory dated 1700. He was working under the Medici's patronage in Florence at the time. Of the instruments he built with his own hand, only three survive, all dating from the 1720s.
The fortepiano has leather-covered hammers, thin strings, and a much lighter case than the modern piano, with no metal frame or bracing in early examples. Its tone is softer with less sustain and varies across registers: slightly buzzing in the bass, tinkling in the high treble, and more rounded in the mid-range. The range of early fortepianos was about four octaves, compared to the much broader range of modern pianos.
Fortepiano is Italian for "loud-soft" and is an abbreviation of Cristofori's original name for the instrument: gravicembalo col piano e forte, meaning "harpsichord with soft and loud." The formal name of the modern piano, pianoforte, reverses the order to "soft-loud." During the age of the fortepiano, the two terms were used interchangeably.
Haydn, Mozart, Beethoven, and Schubert wrote piano music for fortepianos. Mozart wrote for instruments of about five octaves; Beethoven's last piano compositions were for an instrument of about six and a half octaves. The first music composed specifically for the fortepiano was the Sonate da cimbalo di piano by Lodovico Giustini, published in 1732.
The fortepiano became obsolete in the late 18th and 19th centuries as the modern grand piano developed. The early music pioneer Arnold Dolmetsch built three fortepianos in the late 19th century in an attempt at revival, but the effort did not take hold. A major revival occurred in the second half of the 20th century, driven by growing interest in historically informed performance.
Among the most significant fortepiano builders were Gottfried Silbermann in Freiberg, Germany; Johann Andreas Stein and Anton Walter in the Viennese tradition; and John Broadwood in England. Conrad Graf, who lived from 1782 to 1851, made Beethoven's last piano, and his instruments were played by Chopin, Mendelssohn, and Schumann. Chopin preferred pianos by the French maker Pleyel; Liszt favored those by Boisselot.