A harpsichord is a keyboard instrument shaped like a delicate grand piano, in which the strings are plucked by plectra made of quill or leather. The modem concert harpsichord utilizes two keyboards and four sets of strings, two of which are identical in pitch, the third an octave higher, and the fourth an octave lower. The terminology applied to these is borrowed from the organ; thus, the two sets of "normally pitched" strings are called the 8-foot register; the octave higher, the 4-foot; the octave lower, the 16-foot. Each set may be called into play, combined with others, or omitted altogether, and the player can thus create a variety of timbres and colors. Two registers may be sounded on a single keyboard by means of a "coupler," and an additional color resource is available through use of the so-called "lute stop," which activates a set of plectra much nearer the ends of the strings than the regular ones, producing a brilliant, almost harsh sound.
Tone is also affected by the material used for the plectra. Quill creates a sharp, bright sound, but is perishable and varies in quality. Leather, being softer, gives a rounder, fuller tone and is more often used in modern harpsichords.
The origins of the harpsichord are obscure, but it probably can be traced to the psaltery, introduced into Europe by the Moors in the 12th century. The harpsichord itself emerged about the middle of the 15th century, with one keyboard, and by 1500 many were built with two keyboards, each with a set of 8-foot strings. The 4-foot course was added in 1579 and the 16-foot in the late 17th century.
The first prominent harpsichord makers were the Ruckers of Antwerp in the late 1500's. Their style influenced all subsequent makers. The first English builders, in the mid-1600's, introduced pedals (instead of hand knobs) to operate the changes in register and the coupler. The Pleyel harpsichord was made famous during the second quarter of the 20th century primarily through the concertizing of Wanda Landowska.