The harpsichord is a keyboard instrument with strings running from front to back of its wing-shaped horizontal box and soundboard. Unlike the piano and the earlier clavichord with its hammers that strike the strings, the harpsichord has a mechanism by which the strings are plucked. The instrument seems to have existed in a simple form in the 14th century and assumed considerable importance from the early 16th until the fuller development of the pianoforte towards the end of the 18th century. Variations of dynamics on the harpsichord are possible through the use of stops that activate different lengths of string and by the use of a muting buff stop and of the two manuals often found on the instrument. In addition to its ubiquitous use in the music of the baroque period, the harpsichord has also been used by modern composers, since its revival at the end of the 19th century.