The guitar (violao) is a musical instrument that utilizes strings to produce sound. Usually, guitar is made with six strings, but four, seven, eight, ten and twelve string guitars are not rare.

Guitar (violao) is considered as an instrument in many forms of music like blues, country, flamenco, rock and even pop. Acoustically playing, the guitar involves production of the tone by vibration of the string and modulation by the hollow body. Electronic manipulation can also be done on the tone using an amplifier.

Combinations of various woods, with either nylon or steel strings are used for the construction of guitars. The person who makes and repairs string instruments like guitar is called a luthier.

History and development of string instruments similar to guitar (violao) can be traced back to at least 5,000 years. In those days, when synthetic material was not available for making guitars, a guitar was defined as a long, fretted neck, flat wooden soundboard, ribs, and a flat back instrument, most often with incurved sides.

There are two major types of guitars:

Acoustic guitar (violao): A soundboard (present in the front of the guitar body in the form of a piece of wood) is used to produce the sound from this kind of guitars. No external arrangement or device is needed to produce sound. This makes the acoustic guitar quieter than other commonly found band or orchestra instruments and often an external amplifier is used to make the guitar sound audible and to match the sound of other band instruments. The latest range of acoustic guitars come with a host of pick-ups for amplifying and modifying the raw guitar sound.

Within the acoustic guitar type, the sub-categories include: Classical guitars; Flamenco guitars; Steel string guitars (include the flat top or folk guitar); Twelve string guitars; Arch-top guitars; Renaissance or Baroque guitars; Resonator, resophonic or Dobro guitars; Russian guitars; Acoustic bass guitars; Tenor guitars; Harp guitars; Extended range guitars; Guitar battente.

Electric guitars: Electric guitar bodies are solid, semi-hollow or hollow. The sound produced is little and low without amplification. An amplifier forms an integral part of electric guitars. Vibrations of steel strings converted into electric signals by electromagnetic pick-ups are fed in to an amplifier using a cable or radio transmitter. The sound is often modified either using electronic devices or through distortion of valves naturally. The pick-ups here are of two types: single line or double line, each can be either active or passive. Electric guitar sound is most commonly used in jazz, rock-n-roll and blues style of music.

Construction of the guitar (violao) is based on whether the player is left-handed or right-handed. Usually, players use their dominant hand to pluck the strings. For most of the people, it is the right hand. The other hand of the player is on the frets for depressing and gripping guitar strings.

The various major guitar components include: headstock, nut, fretboard, frets, truss rod, inlays, neck, heel or neck joint, strings, guitar body and pickups.

There are certain accessories that might be helpful while playing a guitar (violao). Accessories like: Plectrum - also called the guitar pick, is used for picking the strings. It is made of a plastic like hard material; Slides - used for creating glissando effect in blues and rock genre of music. Neck of a bottle, knife blade or round metal bar, any of these can be used as a slide; Copatasto - it is used for changing pitch of open strings.