Guitar 

The guitar is descended from the lute. Guitars usually have 6 strings, although there are variations on this, the most common being a twelve string guitar. A variety of different tunings are used. The most common by far, known as "standard tuning", is (low to high) E-A-d-g-b-e', which provides a good compromise providing both simple fingering for many chords, and the ability to play common scales with minimal left hand movement. Others such as E-A-d-f#-b-e' (which provides the same intervals as for a lute), D-G-d-g-b-d' ("open G," commonly used for blues or slide guitar) or D-A-d-g-b-e' ("drop D", frequently used by nu metal bands).

Broadly speaking, guitars can be divided into 5 categories:

1. Classical guitars: These are typically strung with nylon or gut, and amplification is provided by the resonant hollow body. They are normally played in a seated position and used to play classical music. Flamenco guitars are almost equal in construction, have a sharper sound, and are used in flamenco.
2. Acoustic guitars: Similar to the Classical guitar, but with a narrower, reinforced neck to sustain the extra tension of steel strings which produce a louder and brighter tone, the acoustic guitar is a staple in folk, traditional and blues music.
3. Electric guitars: Electric guitars have a solid body and produce little sound without amplification. Electromagnetic pickups convert the vibration of the steel strings into electric signals which are fed to an amplifier through a cable or radio device. The sound is frequently modified by other electronic devices or natural distortion of valves in the amplifier. The electric guitar is used extensively in blues and rock and roll, and was invented by Les Paul and independently by Leo Fender[?].
4. 12-string guitars[?] usually have steel strings and are widely used in folk music and rock and roll. Rather than having only six strings, the 12-string guitar has (logically enough) twelve. Each pair of strings is tuned either in unison (the two highest) or an octave apart (the others). They are made both in acoustic and electric forms.
5. Archtop guitars[?] are steel string, acoustic instruments which feature a violin-inspired design in which the top and back of the instrument are carved in a curved rather than a flat shape. Lloyd Loar of the Gibson company invented this variation of guitar after designing a style of mandolin of the same type. They were immediately adopted by both jazz and country musicians, but fell out of style when rock and roll grew popular since their design isn't capable of extreme amplification.

See also: guitarist, bass guitar, Jazz guitar, Chitarrone, Casio guitar[?], Air guitar