A keyboard instrument is a musical instrument played with a musical keyboard. Keyboard instruments can be wind instruments, string instruments, percussion instruments, or electronic instruments.
The most popular keyboard instruments are probably the piano and the synthesizer.
String keyboard instruments:
Among early keyboard instruments are the organ, the clavichord, and the harpsichord. The piano appeared during the 18th century. Early electromechanical instruments, predecessors of the synthesizer, appeared in the early 20th century.