The arpicembalo (harp-harpsichord) of Bartolomeo Cristofori could play notes both loud and quiet, which the harpsichord could not. It was the first piano.
In the 16th century, the harpsichord was the best keyboard instrument you could buy. It essentially worked just like a harp; you pressed a key, and a mechanism plucked a string to produce that distinctive melodic twang. But the harpsichord had its limits. It had, essentially, no volume control. When the mechanism plucked a string, the resulting note was always the same; you couldn’t make it quieter or louder unless you physically changed the design of the instrument.
In the late 16th century, Ferdinando de’ Medici, Grand Prince of Tuscany, employed a young Venetian inventor / musician named Bartolomeo Cristofori. And around the turn of the 17th century, Cristofori created a new instrument. It looked much like a harpsichord, and you could play it in a very similar way. But this instrument did not pluck the strings, it hit them with a small hammer instead. This gave Cristofori’s prototype a super-power. By varying the pressure when you struck the keys, you could play this instrument both soft (piano) and loud (forte).
Cristofori probably called this an arpicembalo – a portmanteau of “harp” (arpa) and “harpsichord” (cembalo). This wasn’t a great name, to be honest: both a harp and a harpsichord are plucked rather than percussed. Another early description was “gravicembalo col piano e forte” – a harpsichord that could play both soft and loud. So people began calling it a fortepiano or pianoforte instead – literally, a loud-soft or a soft-loud. And eventually that contracted to just “piano.”
Cristofori made several arpicembalos, although only three still survive today. The one pictured above – from the Crosby Brown Collection of Musical Instruments in the Metropolitan Museum in New York – is the only one that’s still playable. It’s also the earliest surviving piano.