The tenor guitar or four-string guitar is a slightly smaller, four-string relative of the steel-string acoustic guitar or electric guitar. The instrument was initially developed in its acoustic form by Gibson and C.F. Martin so that players of the four-string tenor banjo could double on guitar.

C.F. Martin & Company is an American guitar manufacturer established in 1833 by Christian Frederick Martin. It is highly respected for its acoustic guitars and is a leading manufacturer of flat top guitars. The company has also made mandolins and tiples, as well as several models of electric guitars and electric basses, although none of these other instruments are still in production.