The classical guitar, also called modern classical guitar, is a member of the guitar family used in classical music and other styles. An acoustic wooden string instrument with strings made of gut or nylon, it is a precursor of the modern steel-string acoustic and electric guitars, both of which use metal strings. Classical guitars derive from instruments such as the lute, the vihuela, the gittern, which evolved into the Renaissance guitar and into the 17th and 18th-century baroque guitar. By the mid-19th century, early forms of the modern classical guitar appear. Today's modern classical guitar was established by the late designs of the 19th-century Spanish luthier, Antonio Torres Jurado.

The steel-string acoustic guitar is a modern form of guitar that descends from the gut-strung Romantic guitar, but is strung with steel strings for a brighter, louder sound. Like the modern classical guitar, it is often referred to simply as an acoustic guitar, or sometimes as a folk guitar.