Source: Source: http://en.wikipedia.org/wiki/harpsihord.htm
The harpsihord may be regarded as a type of piano, while the sets of strings (ie. more than 1 string per pitch) are not struck, but plucked like those of a harp, although not by human fingers, but mechanically by plectra that are triggered from a keyboard. A felt demper prevents the string from continuing to vibrate after being played - through a relatively complex mechanism.
Other related instruments are the virginal (which has only one string per pitch) and spinet (which may be regarded as a harpsichord with strings at an angle form the viewpoint of the musician).
The origin of the harpsichord is unclear, but was perhaps invented in the late middle ages. By the 1500s it was commonly used in Europe.
Source: Source: http://en.wikipedia.org/wiki/harpsihord.htm
http://www.musicianspage.com/audio/instrument/harpsichord/