The earliest precursor of the piano is generally considered to be the dulcimer, a stringed instrument with a trapezoidal soundboard and hammers wielded by the player's hands to strike the strings.
In the late 1600s, Italian instrument maker Bartolomeo Cristofori refined the dulcimer by adding a mechanism that used levers, hammers and dampers to strike the strings. This mechanism allowed for greater control and expressiveness in playing, making it possible to produce notes with varying dynamics and timbre. Cristofori called his invention the "gravicembalo col piano e forte," which means "harpsichord with soft and loud."
During the 18th century, other instrument makers began to experiment with Cristofori's design and introduced further refinements and modifications. In 1711, Cristofori made another significant improvement by adding a mechanism called the "escapement," which allowed the hammers to quickly return to their original position after striking the strings, enabling the player to repeat notes rapidly.
The term "pianoforte," a combination of "piano" (soft) and "forte" (loud), began to be used more widely in the 1700s to describe these new instruments. It eventually shortened to "piano."
Gottfried Silbermann, a German instrument maker, made several important contributions to the development of the piano in the 1700s. He refined the action mechanism, improved the soundboard and stringing, and introduced the use of a wooden frame instead of a wooden case, which resulted in a more robust and stable instrument.
In the early 19th century, English piano maker John Broadwood made further improvements to the piano by introducing a new type of action mechanism that was more responsive and durable. He also experimented with different materials for the strings, soundboards, and frames to enhance the instrument's sound and longevity.
Around the same time, French piano maker Sébastien Érard developed the double escapement action, which allowed for even faster repetition of notes. He also introduced the use of metal frames, which provided greater structural strength and allowed for higher string tension, resulting in a louder and more powerful sound.
Through the 19th and 20th centuries, numerous other innovations and refinements were made to the piano, such as the incorporation of pedals for sustaining and damping the sound, the addition of more octaves, and the development of various action mechanisms.
Therefore, the first piano was not a singular invention, but rather a gradual evolution and refinement of earlier stringed instruments, with contributions from numerous instrument makers over the course of several decades.