The classical guitar (also known as concert guitar, classical acoustic, nylon-string guitar, or Spanish guitar) is the member of the guitar family used in classical music. It is an acoustical wooden guitar with strings made of nylon as opposed to the metal strings used in acoustic and electric guitars. The traditional classical guitar has 12 frets clear of the body and is held on the left leg so that the hand falls at the back of the soundhole (this is called the classical position). The modern steel string guitar, on the other hand, usually has 14 frets clear of the body (see Dreadnought) and is commonly played off the hip.
In addition to the instrument, the phrase "classical guitar" can refer to two other concepts:

• The instrumental finger technique common to classical guitar—individual strings plucked with the fingernails or, rarely, fingertips
• The instrument's classical music repertoire

The shape, construction, and material of classical guitars vary, but typically they have a modern classical guitar shape, or historic classical guitar shape resembling early romantic guitars from France and Italy. Classical guitar strings were once made of catgut and nowadays are made of polymers such as nylon, with a fine silver wire wound on the bass side strings.
A guitar family tree can be identified. The flamenco guitar derives from the modern classical, but has differences in material, construction and sound.[1][2]
The term modern classical guitar is sometimes used to distinguish the classical guitar from older forms of guitar, which are in their broadest sense also called classical, or more specifically: early guitars. Examples of early guitars include the 6-string early romantic guitar (c. 1790–1880), and the earlier baroque guitars with 5 courses.
Today's modern classical guitar was established by the late designs of the 19th-century Spanish luthier Antonio Torres Jurado.