The Mandolin is a musical instrument in the lute family and is usually plucked with a plectrum or "pick". It commonly has four courses of doubled metal strings tuned in unison (8 strings), although five (10 strings) and six (12 strings) course versions also exist.

The most prominent type of mandolin is the Neapolitan, a small lute about 60 cm (2 ft) long with deeply vaulted ribs and a table slanted downward at the lower end. It has four double rib-fastened metal strings suspended across a low bridge and a fretted neck to pegs inserted into a rectangular peg-box. A small flexible plectrum is used to vibrate the strings. A feature of mandolin playing is the constant reiteration of all long pitches, which counteracts its weak sustaining power.

The mandolin evolved in Italy from the medieval/renaissance Mandola, possibly as early as the 15th century but remained obscure until the 18th century, when it was used by, amongst others, Handel in England and Mozart in Vienna.

The fashion subsided in the 19th century but again appeared in Verdi's Otello and was used by Mahler and others. By the turn of the century it had become a popular folk instrument in Germany and America. The mandolin has been used for vocal accompaniment as well as for classical composition since the 18th century.

The modern mandolin has four pairs of strings tuned to violin pitch and produces a clear, bright tone. It is especially popular today in string-band and bluegrass music.