Piano was invented by a maker of musical instruments, Bartolomeo Cristofori, in Italy in the beginning of 18th century. In other words he evolved piano from Harpsichord.
Prior to the invention of the piano, Clavichord and Harpsichord were the primary keyboard instruments date back respectively to 14th and 15th century. Clavichord is one of the simplest and smallest keyboard instruments and Harpsichord varies in shape and it looks similar to a modern grand piano.
Bartolome Cristofori invented an instrument with more easily controlled dynamic range and speed through changing the action of the hammer, whereas the harpsichord’s sound was limited to one, unvarying volume with no dynamics, no softness or loudness.
He called the instrument pianoforte and at the time it had the range of about 4 octaves.
The Cristofori’s piano went through some alterations before it evolved to the modern piano. The early instrument was similar to the modern grand piano. Around 1760 square pianos with horizontal strings similar to the clavichord appeared in London and by 1800 there were upright pianos with perpendicular strings.
One of the important changes in Cristofori piano has made in 1821 by Sebastien Erard. He introduced a double-escapement which allowed fast repetition to be made. Cross stringing was another alteration in 1830 by Alphaeus Babcock. This allowed the strings to fan out over a larger section of the soundboard to give more resonance. Despite many improvements to Cristofori’s piano since 1700, the modern instrument has remained quite similar to the earlier version of it.