The cittern is a stringed instrument dating from the Renaissance, having evolved considerably since that time. It is similar to several other instruments, notably the bouzouki, with which it is often confused.

The Renaissance cittern was one of the few metal-strung plectrum-plucked instruments from the period. Generally four courses (pairs) of strings, the cittern uses a range of only a major 6th between its lowest and highest strings, and employs a "re-entrant" tuning. The tuning and narrow range allow the player a number of simple chord shapes useful for both simple song accompaniment and dances, and its bright and cheerful timbre make it a valuable counterpoint to gut-strung instruments. Other variations on the cittern are the bandore (or bandora), a bass instrument. Likewise the Spanish bandurria, is similar, but also having some characterstics of the more standard lute.

Modern citterns, bouzoukis (zouks), octave mandolins, mandolas, mandocellos , and mandolins are members of a family of instruments distinguished by being strung in 2 string courses with metal strings, usually in unisons but sometimes in octaves, made of wood, usually with a floating bridge/ tailpiece arrangement, and usually tuned in 5ths or open tunings. The body shape is usually teardrop based, rather than the waisted design of a guitar or violin.

A cittern has come to mean usually a 10-string instrument of this family with a short scale length, ie below 22". A bouzouki is usually a 8-string long scale instrument, ie above 22", although 10-string zouks are increasingly common. An octave mandolin is any 8-string zouk/cittern tuned GDAE an octave below the mandolin, a mandola is an alto mandolin traditionally tuned CGDA the same as a viola. A mandocello is a zouk tuned CGDA, like a cello.

The image is a woodcut of a cittern published in 1565 in Adrian Le Roy's "Breve et facile instruction".