The term denotes the whole family of similar plucked-keyboard instruments, including the smaller virginals, muselar, and spinet. The harpsichord was widely used in Renaissance and Baroque music. During the late 18th century, with the rise of the piano, it gradually disappeared from the musical scene. In the 20th century, it made a resurgence, being used in historically informed performances of older music, in new compositions, and in certain styles of popular music.
Harpsichords vary in size and shape, but all have the same basic mechanism. The player depresses a key that rocks over a pivot in the middle of its length. The other end of the key lifts a jack (a long strip of wood) that holds a small plectrum (a wedge-shaped piece of quill, often made of plastic today), which plucks the string. When the player releases the key, the far end returns to its rest position, and the jack falls back; the plectrum, mounted on a tongue that can swivel backwards away from the string, passes the string without plucking it again. As the key reaches its rest position, a felt damper atop the jack stops the string's vibrations. These basic principles are explained in detail below.
Each string is wound around a tuning pin, normally at the end of the string closer to the player. When rotated with a wrench or tuning hammer, the tuning pin adjusts the tension so that the string sounds the correct pitch. Tuning pins are held tightly in holes drilled in the pinblock or wrestplank, an oblong hardwood plank. Proceeding from the tuning pin, a string next passes over the nut, a sharp edge that is made of hardwood and is normally attached to the wrestplank. The section of the string beyond the nut forms its vibrating length, which is plucked and creates sound.
At the other end of its vibrating length, the string passes over the bridge, another sharp edge made of hardwood. As with the nut, the horizontal position of the string along the bridge is determined by a vertical metal pin inserted into the bridge, against which the string rests. The bridge itself rests on a soundboard, a thin panel of wood usually made of spruce, fir or—in some Italian harpsichords—cypress. The soundboard efficiently transduces the vibrations of the strings into vibrations in the air; without a soundboard, the strings would produce only a very feeble sound. A string is attached at its far end by a loop to a hitchpin that secures it to the case.
While many harpsichords have one string per note, more elaborate harpsichords can have two or more strings for each note. When there are multiple strings for each note, these additional strings are called "choirs" of strings. This provides two advantages: the ability to vary volume and ability to vary tonal quality. Volume is increased when the mechanism of the instrument is set up by the player (see below) so that the press of a single key plucks more than one string. Tonal quality can be varied in two ways. First, different choirs of strings can be designed to have distinct tonal qualities, usually by having one set of strings plucked closer to the nut, which emphasizes the higher harmonics, and produces a "nasal" sound quality. The mechanism of the instrument, called "stops" (following the use of the term in pipe organs) permits the player to select one choir or the other. Second, having one key pluck two strings at once changes not just volume but also tonal quality; for instance, when two strings tuned to the same pitch are plucked simultaneously, the note is not just louder but also richer and more complex.