The guitar is a musical instrument with ancient roots that is used in a wide variety of musical styles. It typically has six strings, but four, seven, eight, ten, and twelve string guitars also exist.
Guitars are recognized as one of the primary instruments in blues, country, flamenco, rock music, and many forms of pop. There is also a solo classical instrument. Guitars may be played acoustically, where the tone is produced by vibration of the strings and modulated by the hollow body, or they may rely on an amplifier that can electronically manipulate tone. Such electric guitars were introduced in the 20th century and continue to have a profound influence on popular culture.
Traditionally guitars have usually been constructed of combinations of various woods and strung with animal gut, or more recently, with either nylon or steel strings. Guitars are made and repaired by luthiers.
The acoustic guitar is often played with one or more plectra, or guitar picks, small plates of hard plastic or other material used to strike and strum the strings. Most players use a flat pick held between the thumb and index finger. A few use fingerpicks, picks worn on the thumb and three fingers. Fingerstyle acoustic guitar players use fingerpicks or use their bare fingers and fingernails to strum and strike individual notes.
There are many different variations on the construction of and materials used in acoustic guitars. More expensive guitars feature solid wood tops (usually Sitka spruce) and sides (often Indian rosewood, maple, or mahogany). Entry-level guitars are usually made of laminated wood.
There are several prominent American makers of acoustic guitars. Martin, Taylor, and Gibson are known for both the quality and price of their instruments.
The standard tuning for an acoustic guitar is EADGBE (low to high), although many players, particularly fingerpickers, use alternate tunings, such as "Open G" (DGDGBD), "Open D" (DADF#AD), or "Drop D" (DADGBE).
One variation on the standard acoustic guitar is the 12 string guitar, which sports an additional doubling string for each of the traditional six strings. This guitar was made famous by artists such as Huddie Leadbetter (a.k.a. Leadbelly), Pete Seeger, and Leo Kottke.