The guitar is a musical instrument classified as a fretted string instrument with anywhere from four to 18 strings, usually having six. The sound is projected either acoustically, using a hollow wooden or plastic and wood box (for an acoustic one), or through electrical amplifier and a speaker (for an electric). It is typically played by strumming or plucking the strings with the fingers, thumb or fingernails of the right hand or with a pick while fretting (or pressing against the frets) the strings with the fingers of the left hand. It is a type of chordophone, traditionally constructed from wood and strung with either gut, nylon or steel strings and distinguished from other chordophones by its construction and tuning. The modern guitar was preceded by the gittern, the vihuela, and the five-course baroque one, all of which contributed to the development of the modern six-string instrument.
There are three main types of modern acoustic guitar: the classical (nylon-string), the steel-string acoustic, and the archtop, which is sometimes called a "jazz guitar". The tone of an acoustic one is produced by the strings' vibration, amplified by the hollow body, which acts as a resonating chamber. The classical is often played as a solo instrument using a comprehensive finger-picking technique where each string is plucked individually by the player's fingers, as opposed to being strummed. The term "finger-picking" can also refer to a specific tradition of folk, blues, bluegrass, and country playing in the United States. The acoustic bass one is a low-pitched instrument that is one octave below a regular guitar.