Cristofori built and kept instruments in the court of Prince Ferdinand de' Medici, who had seen on his travels, a large hammer dulcimer being played, and was so enchanted by the wash of tone and the dynamic range, that when he returned, instructed Cristofori to make a keyboard instrument that would be able to play softly (piano) and loudly (forte). So, Cristofori set to the task of developing a new mechanism that would strike the strings, rather than pluck them, as a harpsichord does. This allowed for the volume of the note played to be determined by the force with which that key was pressed. Thus was born an "arpicembalo che fa il piano e il forte" (harpsichord that plays the soft and the loud) or "arpicembalo col piano e forte" (harpsichord with soft and loud). This later became "piano e forte" , then "fortepiano" and eventually simply "piano".

The instrument pictured here was made in Kufstein, Austria by Sebastian Lengerer in 1793. While there are some technical differences from Cristofori's early instruments, overall there were few structural differences. Because of this, along with the fact that the string tensions were increased to produce still greater volume, and the range of notes growing larger, some of the instruments from this period developed what was known as "cheek disease" from the torsion stresses, which caused the cases to twist slightly, as you can see on the right side of this instrument. This problem would later be addressed by the addition of metal plates, resembling a harp, to bear the ever-increasing string loads.