Classification of the piano

Is the piano a percussion instrument because it is struck? Is the piano a stringed instrument like the violin? The classification of musical instruments is a complicated science. Various methods have been used by different writers. The most widely accepted system was published in 1914 by Hornbostel and Sachs. In that system, the piano is listed with the stringed Instruments, or chordophones, under the subcategory "struckboard".
Chordophones are all instruments in which the sound is made by the vibration of strings stretched between fixed points, and Includes the categories lyres, harps, lutes, and zithers. The zither category includes all instruments that consist solely of a string bearer, or of a string bearer with a resonator which is not integral and can be detached without destroying the sound-producing apparatus. Subcategories of zithers Include: simple, plucked board, and struck board. In these categories, the piano has a large number and variety of relatives.

for information about the lute, go the Kenneth Spar's home page
The struckboard zithers include such instruments as the clavichord and dulcimer along with the piano. The dulcimer has been suggested by some to be the direct ancestor of the piano. However, it seems to be more widely accepted that the piano was inspired not by the string category of instruments, but by those that use a keyboard.