The fortepiano was invented by an Italian harpsichord maker, Bartolomeo Cristofori, in Florence 1709.
In his invention, harpsichord jacks (which plucks the strings) are replaced by little hammer which hit the strings (like the tangents in a clavichord) but then immediately fall away, leaving the strings free to vibrate.
The development of this instrument continued throughout the eighteenth century.
Until about 1820, piano construction, as regards materials employed and general physical structure, was similar to harpsichord construction.
In comparison with modern pianos, fortepianos have a softer and more expressive sound and a delicate and sensitive touch.
Listen to this instrument:
Mozart & Beethoven
V. Sofronitsky, R. Brautigam