The guitar is a fretted musical instrument that typically has six strings. It is usually held flat against the player's body and played by strumming or plucking the strings with the dominant hand, while simultaneously pressing selected strings against frets with the fingers of the opposite hand. A plectrum or individual finger picks may also be used to strike the strings. The sound of the guitar is projected either acoustically, by means of a resonant chamber on the instrument, or amplified by an electronic pickup and an amplifier.
The guitar is classified as a chordophone – meaning the sound is produced by a vibrating string stretched between two fixed points. Historically, a guitar was constructed from wood with its strings made of catgut. Steel guitar strings were introduced near the end of the nineteenth century in the United States; nylon strings came in the 1940s.The guitar's ancestors include the gittern, the vihuela, the four-course Renaissance guitar, and the five-course baroque guitar, all of which contributed to the development of the modern six-string instrument.
There are three main types of modern guitar: the classical guitar (Spanish guitar/nylon-string guitar); the steel-string acoustic guitar or electric guitar; and the Hawaiian guitar (played across the player's lap). Traditional acoustic guitars include the flat top guitar (typically with a large sound hole) or an archtop guitar, which is sometimes called a "jazz guitar". The tone of an acoustic guitar is produced by the strings' vibration, amplified by the hollow body of the guitar, which acts as a resonating chamber. The classical Spanish guitar is often played as a solo instrument using a comprehensive fingerstyle 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 guitar playing in the United States.
Electric guitars, first patented in 1937, use a pickup and amplifier that made the instrument loud enough to be heard, but also enabled manufacturing guitars with a solid block of wood needing no resonant chamber. A wide array of electronic effects units became possible including reverb and distortion (or "overdrive"). Solid-body guitars began to dominate the guitar market during the 1960s and 1970s; they are less prone to unwanted acoustic feedback. As with acoustic guitars, there are a number of types of electric guitars, including hollowbody guitars, archtop guitars (used in jazz guitar, blues and rockabilly) and solid-body guitars, which are widely used in rock music.
The loud, amplified sound and sonic power of the electric guitar played through a guitar amp has played a key role in the development of blues and rock music, both as an accompaniment instrument (playing riffs and chords) and performing guitar solos, and in many rock subgenres, notably heavy metal music and punk rock. The electric guitar has had a major 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, ska, mariachi, metal, punk, funk, reggae, rock, grunge, soul, acoustic music, disco, new wave, new age, adult contemporary music, and pop, occasionally used as a sample in hip-hop, dubstep, or trap music.
The modern word guitar and its antecedents have been applied to a wide variety of chordophones since classical times, sometimes causing 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 (qīthārah) and the Latin cithara, which in turn came from the Ancient Greek κιθάρα. This Greek word may also come from the Persian word Sihtar Kithara appears in the Bible four times , and is usually translated into English as harp.
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 a lute-like instrument which is similar to the guitar.
A number of scholars cite many influences 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 four-string oud and its precursor the European lute; the former was brought to Iberia by the Moors in the 8th century. It has often been assumed that the guitar is a development of the lute, or of the ancient Greek kithara. However, many scholars consider the lute an offshoot or separate line of development which did not influence the evolution of the guitar in any significant way.
There were many different plucked instruments that were being invented and used in Europe, during the Middle Ages. By the 16th century, most of the forms of guitar had fallen off, to never be seen again. However, midway through the 16th century, the five-course guitar was established. It was not a straightforward process. There were two types of five-course guitars, differing in the location of the major third and in the interval pattern. The fifth course can be inferred because the instrument was known to play more than the sixteen notes possible with four. The guitar's strings were tuned in unison, so, in other words, it was tuned by placing a finger on the second fret of the thinnest string and tuning the guitar bottom to top. The strings were a whole octave apart from one another, which is the reason for the different method of tuning. Because it was so different, there was major controversy as to who created the five course guitar. A literary source, Lope de Vega's Dorotea, gives the credit to the poet and musician Vicente Espinel. This claim was also repeated by Nicolas Doizi de Velasco in 1640, however this claim has been refuted by others who state that Espinel's birth year (1550) make it impossible for him to be responsible for the tradition. He believed that the tuning was the reason the instrument became known as the Spanish guitar in Italy. Even later, in the same century, Gaspar Sanz wrote that other nations such as Italy or France added to the Spanish guitar. All of these nations even imitated the five-course guitar by "recreating" their own.