A guitar is an instrument that is classified as a string instrument and can hold 4 to 18 strings, usually 6. Use hollow wooden or plastic wooden boxes (for folk guitars) or use electric amplifiers and loudspeakers (for electric guitars) to project sound. It is usually played by playing or plucking the strings with the fingers, thumbs or fingernails of the right hand or by plucking the strings, while at the same time using the fingers of the left hand to fine tune (or compress) the strings. Guitar is a chordophone, traditionally made of wood and strung with gut, nylon or steel strings. Its structure and tone are different from those of other chorodophones. Before using modern guitars, there were keyboards, vibratos, four guitars of the Renaissance and five guitars of Baroque style, all of which contributed to the development of modern six string instruments.

There are three main types of modern folk guitar: Classical Guitar (Nylon Guitar), steel guitar and ARCHTOP guitar, sometimes referred to as "Jazz Guitar". The tone of acoustic guitar is produced by the vibration of strings and amplified by the hollow body of guitar, which acts as a resonant cavity. Classical guitars usually use a comprehensive fingering technique as a solo instrument, in which each string is pulled out by the player's fingers, rather than being plucked. The term "pick fingers" can also refer to specific traditions of performing folk, blues, bluegrass and country guitars in the United States. The acoustic bass guitar is a low-key instrument, eight degrees lower than the ordinary guitar.

The electric guitar, which came out in the 1930s, uses amplifiers and loudspeakers so that the sound of the instrument is loud enough that both the performer and the audience can hear it, and because of the electric signal generated during performance, it can be electronically manipulated and shaped using equalizers (such as bass and treble tone controls) and a variety of electronic effectors to tune, most commonly distortion (or "overload ”）And reverb. Early enhanced guitars used hollow bodies, but in the 1960s and 1970s it was found that solid wood was more suitable because it was not easy to produce unnecessary acoustic feedback "how to call". Like folk guitars, electric guitars come in many types, including hollow guitars, dome guitars (for jazz, blues and rock bands) and solid guitars, which are widely used in rock music.