Modern upright and grand pianos attained their present forms by the end of the 19th century. Improvements have been made in manufacturing processes, and many individual details of the instrument continue to receive attention.
Some Bösendorfer pianos extend the normal range downwards to F0, with one other model going as far as a bottom C0, making a full eight octave range. These extra keys are sometimes hidden under a small hinged lid that can be flipped down to cover the keys in order to avoid visual disorientation in a pianist unfamiliar with the extended keyboard. On others, the colours of the extra white keys are reversed (black instead of white).
