It was invented in Padua Italy, by a guy named Bartolomeo Cristofori. He did this in the very late 1600's; the exact date is not known. The distinctive feature of the piano is the "escapement action", that allows a hammer to strike a wire freely and then recoil back, ready to strike again with the key is played. See link for more details.
Bartolomeo Cristofori created piano
The Piano Tuner was created in 2003.
Tristeza on Piano was created in 1970.
Piano in the Dark was created in 1987.
The Piano Lesson was created in 1995.
Piano in the Background was created in 1960.
Piano in the Foreground was created in 1961.
Wertheim Piano was created in 188#.
Talkin' Piano was created in 2006.
Trilby's Piano was created in 2006.
Around the Piano was created in 1885.
Piano Español was created in 1959.