The piano is the most popular instrument in existence and continues to be the most favored instrument as we enter its fourth century. With each development since its invention, the piano has been able to provide nfinite nuance of expression for the pianist. A complex wooden machine with felt coverings and metal springs are connected with a structure that sustains an average of 20 tons of string tension.
Where did it begin?
Beginning in the 1400s, musicians had only types two keyboards; the clavichord and the harpsichord. Each had its strengths, which made it popular for specific venues and music styles, and it was these, which eventually led to the piano.
In the late 1600's composers were clamoring for an instrument with a broad dynamic range. The answer came from Bartolomeo Cristofori. He was a harpsichord maker from Italy and also maintained the musical instruments at the Medici Court.
Around the year 1700, he produced his greatest invention, the “gravicembalo col piano e forte,” or as we know it today, the piano. Though evidence points to earlier attempts, Cristofori’s was the first successful keyboard instrument which used hammers to hit the strings.
For his new instrument’s hammers, Cristofori used a small roll of parchment with a pad of leather glued on top, fitted into a wood molding. He also added something called the “escapement.” This design allowed the hammer to be thrown freely at the string in the last part of its travel, then escape rather than stay against the string, which allowed the string to vibrate freely. Another innovation was a separate rail for mounting the hammers.
Years passed before Cristofori’s invention was made public. In 1709, an Italian journalist named Scipione Maffei visited Cristofori, publishing drawings of the new design two years later. Instrument builder Gottfried Silbermann saw the sketches and built his version of Cristofori’s design. Eventually, J.S. Bach appraised Silbermann’s work critiqued it, and Silbermann made improvements, which Bach endorsed later on in the 1740s.
There are three surviving Cristofori pianos: one from 1720 which is in the Metropolitan Museum of Art in New York City; one 1722 from the Museo degli Strumenti Musicali in Rome and another from 1726 Cristofori which is in Leipzig, Germany
Source: Piano Technicians Guild - Celebrating 300 Years of the Piano