There are three main types of modern acoustic guitar: the classical guitar (nylon-string guitar), the steel-string acoustic guitar, and the archtop guitar. The tone of an acoustic guitar is produced by the strings' vibration, amplified by the body of the guitar, which acts as a resonating chamber. The classical guitar is often played as a solo instrument using a comprehensive finger-picking technique. The term "finger-picking" can also refer to a specific tradition of folk, blues, bluegrass, and country guitar playing in the United States.
The Guitar Player (c. 1672), by Johannes Vermeer
Electric guitars, introduced in the 1930s, use an amplifier that can electronically manipulate and shape the tone. Early amplified guitars employed a hollow body, but a solid body was eventually found more suitable, as it was less prone to feedback. Electric guitars have had a continuing profound influence on popular culture.
The guitar is used in a wide variety of musical genres worldwide. It is recognized as a primary instrument in genres such as blues, bluegrass, country, flamenco, folk, jazz, jota, mariachi, metal, punk, reggae, rock, soul, and many forms of pop.
Before the development of the electric guitar and the use of synthetic materials, a guitar was defined as being an instrument having "a long, fretted neck, flat wooden soundboard, ribs, and a flat back, most often with incurved sides." The term is used to refer to a number of chordophones that were developed and used across Europe, beginning in the 12th century and, later, in the Americas. A 3,300-year-old stone carving of a Hittite bard playing a stringed instrument is the oldest iconographic representation of a chordophone and clay plaques from Babylonia show people playing an instrument that has a strong resemblance to the guitar, indicating a possible Babylonian origin for the guitar.
The modern word guitar, and its antecedents, has been applied to a wide variety of chordophones since classical times and as such causes confusion. The English word guitar, the German Gitarre, and the French guitare were all adopted from the Spanish guitarra, which comes from the Andalusian Arabic قيثارة qitara, cithara, which in turn came from the Ancient Greek κιθάρα kithara.
The term guitar is descended from the Latin word cithara, but the modern guitar itself is generally not believed to have descended from the Roman instrument. Many influences are cited as antecedents to the modern guitar. Although the development of the earliest "guitars" is lost in the history of medieval Spain, two instruments are commonly cited as their most influential predecessors, the European lute and its cousin, the four-string oud; the latter was brought to Iberia by the Moors in the 8th century.
At least two instruments called "guitars" were in use in Spain by 1200: the guitarra latina (Latin guitar) and the so-called guitarra moresca (Moorish guitar). The guitarra moresca had a rounded back, wide fingerboard, and several sound holes. The guitarra Latina had a single sound hole and a narrower neck. By the 14th century the qualifiers "moresca" or "morisca" and "latina" had been dropped, and these two cordophones were simply referred to as guitars.
The Spanish vihuela, called in Italian the "viola da mano", a guitar-like instrument of the 15th and 16th centuries, is widely considered to have been the single most important influence in the development of the baroque guitar. It had six courses (usually), lute-like tuning in fourths and a guitar-like body, although early representations reveal an instrument with a sharply cut waist. It was also larger than the contemporary four-course guitars. By the 16th century, the vihuela's construction had more in common with the modern guitar, with its curved one-piece ribs, than with the viols, and more like a larger version of the contemporary four-course guitars. The vihuela enjoyed only a relatively short period of popularity in Spain and Italy during an era dominated elsewhere in Europe by the lute; the last surviving published music for the instrument appeared in 1576.
Meanwhile, the five-course baroque guitar, which was documented in Spain from the middle of the 16th century, enjoyed popularity, especially in Spain, Italy and France from the late 16th century to the mid-18th century. In Portugal, the word viola referred to the guitar, as guitarra meant the "Portuguese guitar", a variety of cittern.
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