The harpsichord is a keyboard instrument in which the strings are plucked by a plectrum, rather than hit with a hammer. It preceded the invention of the pianoforte, and was at its height of its popularity between 1500 and 1790.
It is not possible to vary the dynamics (loudness and softness) by striking the keys harder or softer. Instead, some harpsichords have two or more keyboards, each of which can be set to differing loudness and tone quality. This is achieved by pulling out levers placed behind and above the keyboard, called 'stops'. These alter the dynamics by changing the number of strings plucked for a note, or the position along a string where it is plucked. Some harpsichords have foot pedals to operate the stops, leaving both hands free to play on the keyboard.
The harpsichord has declined greatly in popularity since the 18th century, because the pianoforte is a superior instrument, having the fundamental advantage that loud and soft sounds are obtained merely by altering the touch.
The sound of the harpsichord is light and tinkly, a bit metallic, and is well suited to baroque music, such as that of Bach. It was employed in the baroque period, with violins and chamber ensembles, to provide a chordal backing, called a 'continuo'. Modern MIDI sound cards and sound modules can generate a very effective harpsichord sound.
The shape of the harpsichord resembles that of a modern grand piano, with the strings at a right-angle to the keyboard. It is a large piece of furniture, needing plenty of space, and it is also expensive to manufacture. Smaller and cheaper instruments were made in the 16th to 18th centuries, for use in homes. These were called spinets and virginals.