Guitar-Electric

An electric guitar is a guitar that uses the principle of electromagnetic induction to convert vibrations of its metal strings into electric signals. Since the generated signal is too weak to drive a loudspeaker, it is amplified before sending it to a loudspeaker. Since the output of an electric guitar is an electric signal, the signal may easily be altered using electronic circuits to add color to the sound. Often the signal is modified using effects such as reverb and distortion. Arguably, no other musical instrument has had more of an impact on how music has evolved since the beginning of the twentieth century than the electric guitar. Conceived in 1931, the electric guitar became a necessity as jazz musicians sought to amplify their sound. Since then, it has evolved into a stringed musical instrument capable of a multitude of sounds and styles. It served as a major component in the development of rock and roll and countless other genres of music.

History
Various experiments at electrically amplifying the vibrations of a string instrument date back to the early part of the twentieth century. Patents from the 1910s show telephone transmitters adapted and placed inside violins and banjos to amplify the sound. Hobbyists in the 1920s used carbon button microphones attached to the bridge, however these detected vibration from the bridge on top of the instrument, resulting in a weak signal. With numerous people experimenting with electrical instruments in the 1920s and early 1930s, there are many claimants to have been the first to invent an electric guitar.

Electric guitars were originally designed by luthiers, guitar makers, electronics enthusiasts, and instrument manufacturers. Guitar innovator Les Paul experimented with microphones attached to guitars. Some of the earliest electric guitars adapted hollow bodied acoustic instruments and used tungsten pickups. An electrically amplified guitar was developed by George Beauchamp in 1931. Commercial production began in late summer of 1932 by Electro-Patent-Instrument Company Los Angeles, a partnership of Adolph Rickenbacker, Paul Barth and George Beauchamp, the inventor. The wooden body of the prototype was built by Harry Watson, a craftsman who had worked for the National Resophonic Guitar Company (where the men met). By 1934 the company was renamed Rickenbacker Electro Stringed Instrument Company.

The need for the amplified guitar became apparent during the big band era as orchestras increased in size, particularly when guitars had to compete with large brass sections. The first electric guitars used in jazz were hollow archtop acoustic guitar bodies with electromagnetic transducers. By 1932 an electrically amplified guitar was commercially available. Early electric guitar manufacturers include: Rickenbacker (first called Ro-Pat-In) in 1932, Dobro in 1933, National, AudioVox and Volu-tone in 1934,Vega, Epiphone (Electrophone and Electar), and Gibson in 1935 and many others by 1936.

The solid body electric guitar is made of solid wood, without functionally resonating air spaces. Rickenbacher, later spelled Rickenbacker, offered a cast aluminum electric steel guitar, nicknamed "The Frying Pan" or "The Pancake Guitar", developed in 1931 with production beginning in the summer of 1932. This guitar sounds quite modern and aggressive as tested by vintage guitar researcher John Teagle. The company Audiovox built and may have offered an electric solid-body as early as the mid-1930s.

The first solid body "Spanish" standard guitar was offered by Vivi-Tone no later than 1934. An example of this model, featuring a guitar-shaped body of a single sheet of plywood affixed to a wood frame, can be seen in the Experience Music Project. Another early, substantially solid Spanish electric guitar, called Electro Spanish, was marketed by the "Rickenbacker" guitar company in 1935 and made of Bakelite. By 1936, the Slingerland company introduced a wooden solidbody electric model.

The earliest documented performance with an electrically amplified guitar was in 1932, by Gage Brewer. The Wichita, Kansas-based musician had an Electric Hawaiian A-25 (frypan, lap-steel) and a standard Electric Spanish from George Beauchamp of Los Angeles, California. Brewer publicized his new instruments in an article in the Wichita Beacon of October 2, 1932 and through performances that month. Brewer's original 1932 Ro-Pat-In Electro Spanish guitar can currently be viewed at the Wichita-Sedgwick County Historical Museum.

The first recordings using the electric guitar were by Hawaiian style players, including Andy Iona in 1933. Bob Dunn of Milton Brown's Musical Brownies introduced the electric Hawaiian guitar to Western Swing with his January 1935 Decca recordings, departing almost entirely from Hawaiian musical influence and heading towards Jazz and Blues. Alvino Rey was an artist who took this instrument to a wide audience in a large orchestral setting and later developed the pedal steel guitar for Gibson. An early proponent of the electric Spanish guitar was jazz guitarist George Barnes who used the instrument in two songs recorded in Chicago on March 1, 1938, "Sweetheart Land" and "It's a Low-Down Dirty Shame". Some incorrectly attribute the first recording to Eddie Durham, but his recording with the Kansas City Five was 15 days later. Durham introduced the instrument to a young Charlie Christian, who made the instrument famous in his brief life and would be a major influence on jazz guitarists for decades thereafter.

Gibson's first production electric guitar, marketed in 1936, was the ES-150 model ("ES" for "Electric Spanish"; and "150" reflecting the $150 price of the instrument, along with a matching amplifier). The ES-150 guitar featured a single-coil, hexagonally shaped "bar" pickup, which was designed by Walt Fuller. It became known as the "Charlie Christian" pickup (named for the great jazz guitarist who was among the first to perform with the ES-150 guitar). An early commercially successful solid-body electric guitar was the Fender Esquire in 1950.

<!-- I've comment this out. It seems apocryphal, and there are good secondary sources to electrification 20years before this

Steel guitarist Bob Dunn from Beggs, Oklahoma is credited as the first to electrify his guitar. A possibly apocryphal story relates that Dunn hooked his guitar up to a car battery during an outdoor dance in order to be heard. However, historian Kevin Reed Coffey indicates that Dunn wanted to accomplish more than volume with electrification. He writes, “Not content with just being louder, Dunn experimented with ways to capture the brassy resonance of jazz horns. According to surviving contemporaries, he emulated musicians such as Texas trombonist Jack Teagarden and the great trumpeter Louis Armstrong, and his approach to the steel was based on their styles, their tone, their phrasing and attack.” Bill C. Malone in Country Music USA writes, “Dunn converted a standard round-hole Martin guitar into an electric instrument by magnetizing the strings and raising them high off the box. He then attached an electric pickup to the guitar, which in turn was connected to a Vol-U-Tone amplifier.” Dunn’s first use of electric guitar on a recording was in 1935.

The first recording of an electric Spanish guitar, west of the Mississippi was in Dallas, in September 1935, during a session with Roy Newman and His Boys, an early Western swing dance band. Their guitarist, Jim Boyd, used his electrically amplified guitar during the recording of three songs, "Hot Dog Stomp" (DAL 178-Vo 03371), "Shine On, Harvest Moon" (DAL 180-Vo 03272), and "Corrine, Corrina" (DAL 181-Vo/OK 03117). An even earlier Chicago recording of an electrically amplified guitar—albeit an amplified lap steel guitar—was during a series of session by Milton Brown and His Brownies (another early Western swing band) that took place January 27–28, 1935, wherein Bob Dunn played his amplified Hawaiian guitar. --> Early proponents of the electric guitar on record include: Jack Miller (Orville Knapp Orchestra), Alvino Rey (Phil Spitalney Orchestra), Les Paul (Fred Waring Orchestra), Danny Stewart (Andy Iona Orchestra), George Barnes (under many aliases), Floyd Smith, Big Bill Broonzy, T-Bone Walker, George Van Eps, Charlie Christian (Benny Goodman Orchestra) Tampa Red, Memphis Minnie, and Arthur Crudup.

A functionally solid body electric guitar was designed and built by Les Paul from an Epiphone acoustic archtop. His "log guitar" (so called because it consisted of a simple 4x4 wood post with a neck attached to it and homemade pickups and hardware, with two detachable Swedish hollow body halves attached to the sides for appearance only) shares nothing in design or hardware with the solid body "Les Paul" model sold by Gibson. However, the feedback problem associated with hollow-bodied electric guitars was understood long before Paul's "log" was created in 1940; Gage Brewer's Ro-Pat-In of 1932 had a top so heavily reinforced that it essentially functioned as a solid-body instrument.

In 1945, Richard D. Bourgerie made an electric guitar pickup and amplifier for professional guitar player George Barnes. Bourgerie worked through World War II at Howard Radio Company making electronic equipment for the American military. Barnes showed the result to Les Paul, who then arranged for Bourgerie to have one made for him.

Construction
[[image:Electric Guitar (Superstrat based on ESP KH - vertical) - with hint lines and numbers.png|thumb|Legend:

1. Headstock:

1.1 machine heads

1.2 truss rod cover

1.3 string guide

1.4 nut

2. Neck:

2.1 fretboard

2.2 inlay fret markers

2.3 frets

2.4 neck joint g 3. Body

3.1 "neck" pickup

3.2 "bridge" pickup

3.3 saddles

3.4 bridge

3.5 fine tuners

3.6 tremolo arm (whammy bar)

3.7 pickup selector switch

3.8 volume and tone control knobs

3.9 output connector (input jack)

3.10 strap buttons

4. Strings:

4.1 bass strings

4.2 treble strings]] While guitar construction has many variations, in terms of the materials used for the body, the shape of the body, and the configuration of the neck, bridge, and pickups, there are features which are found in almost every guitar. The photo below shows the different parts of an electric guitar. The headstock (1) contains the metal machine heads, which are used for tuning; the nut (1.4), a thin fret-like strip of metal, plastic, graphite or bone which the strings pass over as they first go onto the fingerboard; the machine heads (1.1), which are worm gears which the player turns to change the string tension and thus adjust the tuning; the frets (2.3), which are thin metal strips which stop the string at the correct pitch when a string is pressed down against the fingerboard; the truss rod (1.2), a metal cylinder used for adjusting the tension on the neck (not found on all instruments); decorative inlay (2.2), a feature not found on lower-cost instruments.

The neck and the fretboard (2.1) extend from the body; at the neck joint (2.4), the neck is either glued or bolted to the body; the body (3) of this instrument is made of wood which is painted and lacquered, but some guitar bodies are also made of polycarbonate or other materials; pickups (3.1, 3.2), which are usually magnetic pickups, but which may also be piezoelectric transducer pickups; the control knobs (3.8) for the volume and tone potentiometers; a fixed bridge (3.4) -on some guitars, a spring-loaded hinged bridge called a "tremolo system" is used instead, which allows players to "bend" notes or chords down in pitch or perform a vibrato embellishment; and a plastic pickguard, a feature not found on all guitars, which is used to protect the body from scratches or cover the control cavity which holds most of the electric guitar's wiring.

The wood that the body (3) is made of is a very disputed subject considered by some to largely determine the sonic qualities of the guitar, while others believe that the sonic difference in a solid body guitar is very subtle between woods. In acoustic and archtop guitars there is a more pronounced sonic definition caused by the type of wood used. Typical woods include alder (brighter, but well rounded), swamp ash (similar to alder, but with more pronounced highs and lows), mahogany (dark, bassy, warm), poplar (similar to alder) and basswood (very neutral). Maple, a very bright tonewood, is also a popular body wood, but is very heavy. For this reason it is often placed as a 'cap' on a guitar made of primarily of another wood. Cheaper guitars are often made of cheaper woods, such as plywood, pine or agathis, not true hardwoods, which can affect the durability and tone of the guitar.Although most guitars are made from wood, any material may be used in the construction of a guitar. Materials such as plastic or cardboard are examples of unusual but possible materials that affect the overall sound of the guitar.

Pickups
Compared to an acoustic guitar, which has a hollow body, electric guitars make comparatively little audible sound simply by having their strings plucked, and so electric guitars are normally plugged into a guitar amplifier, which makes the sound louder. When an electric guitar is strummed, the movement of the strings generates (i.e., "induces") a very small electric current in the magnetic pickups, which are magnets wrapped with coils of very fine wire. That current is then sent through a cable to a guitar amplifier. The current induced is proportional to such factors as the density of the string or the amount of movement over these pickups. That vibration is, in turn, affected by several factors, such as the composition and shape of the body. Some "hybrid" electric-acoustic guitars are equipped with additional microphones or piezoelectric pickups (transducers) that sense mechanical vibration from the body. Because in some cases it is desirable to isolate the pickups from the vibrations of the strings, a guitar's magnetic pickups will sometimes be embedded or "potted" in epoxy or wax to prevent the pickup from having a microphonic effect.

Because of their natural inductive qualities, all magnetic pickups tend to pick up ambient and usually unwanted electromagnetic noises. The resulting noise, the so-called "hum", is particularly strong with single-coil pickups, and aggravated by the fact that very few guitars are correctly shielded against electromagnetic interference. The most frequent cause is the strong 50 or 60 Hz component that is inherent in the generation of electricity in the local power transmission system. As nearly all amplifiers and audio equipment associated with electrical guitars rely on this power, there is in theory little chance of completely eliminating the introduction of unwanted hum.

Double-coil or "humbucker" pickups were invented as a way to reduce or counter the unwanted ambient hum sounds (known as 60 cycle hum). Humbuckers have two coils of opposite magnetic and electric polarity. This means that electromagnetic noise hitting both coils should cancel itself out. The two coils are wired in phase, so the signal picked up by each coil is added together. This high combined inductance of the two coils leads to the richer, "fatter" tone associated with humbucking pickups. Optical pickups are a type of pickup which sense string and body vibrations using infrared LED light.

Vibrato arms
Some electric guitars have a tremolo arm (sometimes called a "whammy bar" or "vibrato arm" and occasionally abbreviated as trem), a lever attached to the bridge which can slacken or tighten the strings temporarily, changing the pitch, thereby creating a vibrato or a portamento effect. The name "tremolo bar" is somewhat misleading. It would be more accurate and appropriate to call it a vibrato bar. Tremolo is a fluctuation of volume. Vibrato is a fluctuation of pitch, which is what the whammy bar produces. Early vibrato systems, such as the Bigsby vibrato tailpiece, tended to be unreliable and cause the guitar to go out of tune quite easily, and also had a limited range. Later Fender designs were better, but Fender held the patent on these, so other companies used Bigsby-style vibrato for many years.

With the expiration of the Fender patent on the Stratocaster-style vibrato, various improvements on this type of internal, multi-spring vibrato system are now available. Floyd Rose introduced one of the first improvements on the vibrato system in many years when in the late 1970s he began to experiment with "locking" nuts and bridges which work to prevent the guitar from losing tuning even under the most heavy whammy bar acrobatics.

Guitar necks
Electric guitar necks can vary according to composition as well as shape. The primary metric used to describe a guitar neck is the scale, which is the overall length of the strings from the nut to the bridge. A typical Fender guitar uses a 25.5 inch scale, while Gibson uses a 24.75 inch scale in their Les Paul. While Gibson's scale has often claimed to be 24.75", it has varied through the years by as much as a half inch. The frets are placed proportionally according to the scale length; thus, the smaller the scale, the tighter the spacing of the frets.

Necks are described as bolt-on, set-in, or neck-through depending on how they are attached to the body. Set-in necks are glued to the body in the factory, and are said to have a warmer tone and greater sustain; this is the most traditional type of joint. Bolt-on necks were pioneered by Leo Fender to facilitate easy adjustment and replacement of the guitar neck. Neck-through instruments extend the neck itself to form the center of the guitar body, and are known for long sustain and for being particularly sturdy. While a set neck can be carefully unglued by a skilled luthier, and a bolt-on neck can simply be unscrewed, a neck-through design is difficult or even impossible to repair, depending on the damage. Historically, the bolt-on style has been more popular for ease of installation and adjustment; since bolt-on necks can be easily removed, there is an after-market in replacement bolt-on necks from companies such as Warmoth and Mighty Mite. Some instruments, notably most Gibson models, have continued to use set/glued necks. Neck-through bodies are somewhat more common in bass guitars.

The materials used in the manufacture of the neck have great influence over the tone of the instrument. Hardwoods are very much preferred, with maple, ash, and mahogany topping the list. The neck and fingerboard can be made from different materials, such as a maple neck with a rosewood fingerboard. In the 1980s, exotic man-made materials such as graphite began to be used, but are pricey and never have replaced wood in production instruments. Such necks can be retrofitted to existing bolt-on instruments.

There are several different neck shapes used on guitars, including shapes known as C necks, U necks, and V necks. These refer to the cross-sectional shape of the neck (especially near the nut). There are also several sizes of fret wire available, with traditional players often preferring thin frets, and metal shredders liking thick frets. Thin frets are considered better for playing chords, while thick frets allow lead guitarists to bend notes with less effort. An electric guitar with a neck which folds back called the "Foldaxe" was designed and built for Chet Atkins by Roger C. Field (featured in Atkins' book "Me and My Guitars."). Steinberger guitars developed a line of exotic instruments without headstocks, with tuning done on the bridge instead.

Sound and effects
While an acoustic guitar's sound is largely dependent on the vibration of the guitar's body and the air within it, the sound of an electric guitar is largely dependent on a magnetically induced electrical signal, generated by the vibration of metal strings near sensitive pickups. The signal is then "shaped" on its path to the amplifier by using a range of effect devices or circuits that modify the tone and characteristics of the signal. The amplifiers and speakers used also add (intentional) coloration to the final sound.

Built-in sound shaping
Electric guitars can have up to three magnetic pickups. Identical pickups will have different tones depending on how near they are to the neck or bridge, with bridge pickups having a bright or trebly timbre, and neck pickups being more warm or bassy. The type of pickup also affects tone, with dual-coil pickups sounding warmer, thicker, perhaps even muddy, and single coil pickups sounding clear, bright, perhaps even biting. Guitars do not have to be fitted with a uniform type of pickup: a common mixture is the "fat strat" arrangement of one dual-coil at the bridge position, with single coils in the middle and neck positions.

Where there is more than one pickup, selector switching is fitted. These often allow the outputs of two or more pickups to be combined, so that two-pickup guitars have three-way switches, and three-pickup guitars have five-way switches. Further circuitry is sometimes provided to combine the pickups in different ways. For instance, phase switching places one pickup out of phase with the other(s), leading to a "honky", "nasal", or "funky" sound. Individual pickups can also have their timbre altered by switches, typically coil tap switch, which effectively short-circuits some of a dual-coil pickup's windings, giving a tone like a single coil pickup.

The final stages of on-board sound-shaping circuitry are the volume control (potentiometer) and tone control (which "rolls off" the treble frequencies). Where there are individual volume controls for different pickups, and where pickup signals can be combined, they would affect the timbre of the final sound by adjusting the balance between pickups from a straight 50:50.

The strings fitted to the guitar also have an influence on tone. Rock musicians often prefer the lightest gauge of roundwound string, which are easier to bend, while jazz musicians go for heavier, flatwound strings with a rich, dark sound.

Recent guitar designs may incorporate much more complex circuitry than described above: see Digital and synthesizer guitars, below.

Classic amplifier sounds
In the 1960s, some guitarists began exploring a wider range of tonal effects by distorting the sound of the instrument. To do this, they used overdrive &mdash; increasing the gain, of the preamplifier beyond the level at which the signal could be faithfully reproduced, resulting in a "fuzzy" sound. This effect is called "clipping" by sound engineers, because when viewed with an oscilloscope, the wave forms of a distorted signal appear to have had their peaks "clipped off", approximating a square wave. This was not actually a new development in the instrument, but rather a shift of aesthetics, the sound having not been recognized as desirable previously.

Distortion achieved by overdrive necessarily involves high volumes and is therefore often combined with audio feedback.

After distortion became popular, amplifier manufacturers included various provisions for it, making amps easier to overdrive, and providing separate "dirty" and "clean" channels so that distortion could easily be switched in and out. The distortion characteristics of vacuum tube amplifiers are particularly sought-after, and various attempts have been made to emulate them without the disadvantages (fragility, low power, expense) of actual tubes.

Guitar amplifiers have long included at least a few effects, often tone controls and a spring reverb unit. The use of offboard effects is assisted by the provision of effect loops, an arrangement that allows effects to be taken out of circuit when not required.

Effects units
In the 1960s, the tonal palette of the electric guitar was further modified by introducing an Effects unit in its signal path. modifiers, wave-shaping circuits, voltage-controlled oscillators, or digital delays. Effects units come in several formats, the most common of which are the stomp-box and the rack-mount unit. A "stomp box" (or "pedal") is a small metal or plastic box containing the circuitry which is placed on the floor in front of the musician and connected in line with the patch cord connected to the instrument. The box is typically controlled by one or more foot-pedal on-off switches and it typically contains only one or two effects. "Guitar pedalboards" are used by musicians who use multiple stomp-boxes; these may be a DIY project made with plywood or a commercial pedalboard.

A rack-mount effects unit may contain the identical electronic circuit, but is mounted in a standard 19" equipment rack. Usually, however, rack-mount effects units contain several different types of effects.  They are typically controlled by knobs or switches on the front panel, and often by a MIDI digital control interface.

Typical effects include:-
 * Effects such as stereo chorus, phasers and flangers which shift the pitch of the signal by a small and varying amount, creating swirling, shimmering and whooshing noises.
 * Effects such as octavers, which displace pitch by an exact musical interval.
 * Distortion, such as transistor-style fuzz, or effects incorporating or emulating vacuum tube distortion.
 * Filters such as wah-wah
 * Envelope shapers, such as compression/sustain or volume/swell.
 * Time-shift effects such as delay and reverb.

Not all special effects are electronic; in 1967, guitarist Jimmy Page of The Yardbirds and Led Zeppelin created unusual, psychedelic sound effects by playing the electric guitar using a violin bow.

Modern amplifier techniques
In the 1970s, as effects pedals proliferated, their sounds were combined with tube amp distortion at lower, more controlled volumes by using power attenuators such as Tom Scholz' Power Soak as well as re-amplified dummy loads such as Eddie Van Halen's use of a variac, power resistor, post-power-tube effects, and a final solid-state amp driving the guitar speakers. A variac is one approach to power-supply based power attenuation, to make the sound of power-tube distortion more practically available.

Recent amplifiers may include digital technology similar to modern effects pedals, including the ability to model or emulate a variety of classic amps.

Digital and software-based effects
A multi-effects device (also called a "multi-FX" device) is a single electronics effects pedal or rackmount device that contains many different electronic effects. In the late 1990s and throughout the 2000s, multi-FX manufacturers such as Zoom and Korg produced devices that were increasingly feature-laden. Multi-FX devices allow several of the effects to be used together, and most devices allow users to set "preset" combinations of different effects including distortion, chorus, reverb, compression, and so on. This allows musicians to have quick on-stage access to different effects combinations. Some multi-FX pedals contain modelled versions of well-known effects pedals or amplifiers. Multi-effects devices have garnered a large share of the effects device market because they offer the user such a large variety of effects in a single package. A low-priced multi-effects pedal may provide 20 or more effects for the price of a regular single-effect pedal. More expensive multi-effect pedals may include 40 or more effects, amplifier modelling, and the ability to combine effects and/or modelled amp sounds in different combinations, as if the user was using multiple guitar amps. More expensive multi-effects pedals may also include more input and output jacks (e.g., an auxiliary input or a "dry" output), MIDI inputs and outputs, and an expression pedal, which can control volume or modify effect parameters (e.g., the rate of the simulated rotary speaker effect).

By the 1980s and 1990s, software effects became capable of replicating the analog effects used in the past. These new digital effects attempted to model the sound produced by analog effects and tube amps, to varying degrees of quality. There are many free guitar effects computer programs for computers that can be downloaded via the Internet. Now, computers with sound cards can be used as digital guitar effects processors. Although digital and software effects offer many advantages, many guitarists still use analog effects.

Synthesizer and digital guitars
In 2002, Gibson announced the first digital guitar, which performs analog-to-digital conversion internally. The resulting digital signal is delivered over a standard Ethernet cable, eliminating cable-induced line noise. The guitar also provides independent signal processing for each individual string. Also, in 2003 amp maker Line 6 released the Variax guitar. It differs in some fundamental ways from conventional solid-body electrics. For example it uses piezoelectric pickups instead of the conventional electromagnetic ones, and has an on-board computer capable of modifying the sound of the guitar to model the sound of many instruments.

Playing techniques
The sound of a guitar is not only adapted by electronic sound effects, but also heavily by all kinds of new techniques developed or becoming possible in combination with the electric amplification. This is called extended technique.

Extended techniques include:-
 * String bending (or radial finger vibrato.). This is not quite unique to the electric instrument, but is greatly facilitated by the light strings typically used on solid body guitars.
 * The use of the whammy bar or "tremolo" arm, including the extreme technique of dive bombing.
 * Tapping, in which both hands are applied to the fretboard. This is only feasible with the assistance of amplification.
 * Pinch harmonics.
 * Volume swells, in which the volume knob is repeatedly rolled to create a violin-like sound. Note that the same result can also be accomplished through the use of an external swell pedal, although the knob technique can enhance showmanship and conveniently eliminate the need for another pedal.
 * Use of audio feedback to enhance sustain and change timbre.
 * Substitution of another device for the plectrum, for instance the violin bow (as famously used by Jimmy Page) and the e-bow, (a device using electromagnetic feedback to vibrate strings without direct contact). Like feedback, these techniques increase sustain, bring out harmonics and change the acoustic envelope.
 * Sustainers built into the guitar itself.
 * Use of slide or bottlenecks.
 * Sometimes guitars are even adapted with extra modifications to alter the sound, such as Prepared guitar and 3rd bridge.

Other techniques such as axial finger vibrato, pull-offs, hammer-ons, palm muting, harmonics and altered tunings are also used on the classical and acoustic guitar. Shred guitar is a genre involving a number of extended techniques.

Solid body
Solid body electric guitars have no hollow internal cavity to accommodate vibration and no sound holes such as those used to amplify string vibrations in acoustic guitars. Solid body instruments are generally made up of hardwood with a lacquer coating. The wood is dried for 3 to 6 months in heated storage before being cut to shape. The sound that is audible in music featuring electric guitars is produced by pickups on the guitar that convert the string vibrations into an electrical signal. The signal is then fed to an amplifier (or amp) and speaker.

One of the first solid body guitars was invented by Les Paul. Gibson did not present their 'Les Paul' guitar prototypes to the public, as they did not believe it would catch on. The first mass-produced solid-body guitar was Fender's Broadcaster (later to become the 'Telecaster') first made in 1948, five years after Les Paul made his prototype. The Gibson Les Paul appeared soon after to compete with the Broadcaster.

String-through body
When discussing electric guitar construction, the term string-through body is used to describe a type of solid body electric guitar body in which the strings are threaded through holes drilled into the bottom of the guitar body. The strings are typically held in place using metal ferrules screwed or glued into the holes.

The advantages of a string-through body mostly relate to improvements in a guitar's sustain and timbre. It is also by nature impossible to install a tremolo arm and have the string ends anchored through the body. Tremolo systems change string tension by changing the physical length of the string. This requires the end of the string to be anchored to the (tremolo) bridge unit directly, instead of to the wood of the body. [A talented guitar luthier or repair person is certainly capable of installing a tremolo bridge on this type of guitar, however, this is rarely done as it eliminates whatever tonal benefits are provided by the string-through body system and permanently degrades the value and collectability of the original instrument.]

Examples of string-through bodies on guitars include the Fender Telecaster Thinline and Telecaster Deluxe.

Semi-acoustic
These guitars have a hollow body and electronic pickups mounted on its body. They work in a similar way to solid body electric guitars except that because the hollow body also vibrates, the pickups convert a combination of string and body vibration into an electrical signal. A variant form, the semi-hollow body guitar, strikes a balance between the characteristics of solid-body and hollow-body guitars. Advocates of semi-hollow-body guitars argue that they have greater resonance and sustain than true solid-body guitars, as a solid wood body. Several metal bodies were made in the 1950s by violin and cello makers. In the 1970s, John Veleno made a polished aluminum guitar. Liquid Metal Guitars makes a metal body guitar made out of a solid block of aluminum and then chrome or gold-plates the instrument.

Chambered
Many guitars otherwise sold as solid-bodied instruments, such as the Gibson Les Paul or the PRS Singlecut, are built with "weight relief" holes bored into the body which affect the sound of the instrument. The Les Paul Supreme edition is currently described by the manufacturer as a "chambered" instrument, with a weight relief system designed to positively effect the sound.

Electric acoustic
Some steel-string acoustic guitars are fitted with pickups purely as an alternative to using a separate microphone. They may also be fitted with a piezoelectric pickup under the bridge, attached to the bridge mounting plate, or with a low mass microphone (usually a condenser mic) inside the body of the guitar that will convert the vibrations in the body into electronic signals, or even combinations of these types of pickups, with an integral mixer/preamp/graphic equalizer. These are called electric acoustic guitars, and are regarded as acoustic guitars rather than electric guitars because the pickups do not produce a signal directly from the vibration of the strings, but rather from the vibration of the guitar top or body.

These should not be confused with semi-acoustic guitars, which have pickups of the type found on solid body electric guitars, or solid-bodied hybrid guitars with piezoelectric pickups.

String, bridge, and neck variants
Although rare, the one-string guitar is sometimes heard, particularly in Delta blues, where improvised folk instruments were popular in the 1930s and 1940s. Eddie "One String" Jones had some regional success with a Mississippi blues musician Lonnie Pitchford played a similar, homemade instrument. In a more contemporary style, Little Willie Joe, the inventor of the Unitar, had a rhythm and blues instrumental hit in the 1950s with "Twitchy", recorded with the Rene Hall Orchestra. The best-known exponent of the four-string guitar, often called the tenor guitar was Tiny Grimes, who played on 52nd Street with the beboppers and played a major role in the Prestige Blues Swingers. Grimes' guitar omitted the bottom two strings. Deron Miller of CKY only uses four strings, but plays a six string guitar with the two highest strings removed. Many banjo players use this tuning: DGBE, mostly in Dixieland. Guitar players find this an easier transition than learning plectrum or tenor tuning.

Seven-string
Most Seven-string guitars add a low "B" string below the low "E". Both electric and classical guitars exist designed for this tuning. A high "A" string above the high "E" instead of the low "B" is sometimes used. Another less common seven-string arrangement is a second G string situated beside the standard G string and tuned an octave higher, in the same manner as a twelve-stringed guitar (see below). Jazz guitarists using a seven-string include veteran jazz guitarists George Van Eps, Bucky Pizzarelli and his son John Pizzarelli.

Seven-string electric guitars were popularized among rock players in the 1980s by Steve Vai. Along with the Japanese guitar company Ibanez, Vai created the Universe series seven string guitars in the 1980s, with a double locking tremolo system for a seven string guitar. These models were based on Vai's six string signature series, the Ibanez Jem. Seven-string guitars experienced a resurgence in popularity in the 2000s, championed by Limp Bizkit, Slayer, KoRn, Fear Factory, Strapping Young Lad, Nevermore, Muse and other hard rock/metal bands. Metal musicians often prefer the seven-string guitar for its extended lower range. The seven-string guitar has also played an essential role in progressive metal rock, and is commonly used in bands such as Dream Theater, Pain of Salvation and by experimental guitarists such as Ben Levin.

Eight and nine-string
Eight-string electric guitars are rare, but not unused. One is played by Charlie Hunter (manufactured by Novax Guitars). The largest manufacturer of 8- to 14-strings is Warr Guitars. Their models are used by Trey Gunn (ex King Crimson) who has his own signature line from the company. Also, Mårten Hagström and Fredrik Thordendal of Meshuggah used 8-string guitars made by Nevborn Guitars and now guitars by Ibanez. Munky of nu metal band KoRn is also known to use seven-string Ibanez guitars and it is rumored that he is planning to release a K8 eight-string guitar similar to his K7 seven-string guitar. Stephen Carpenter of Deftones also switched from 7 to 8 string in 2008 and released his signature STEF B-8 with ESP Guitars. In 2008 Ibanez released the Ibanez RG2228-GK which is the first mass produced eight-string guitar. Jethro Tull's first album uses a nine-string guitar on one track. Minarik Guitars manufactures the "Inferno V" 9 stringed guitar that has the top three strings doubled up with strings that are an octave higher, like 12 stringed guitars. Bill Kelliher, guitarist for the heavy metal group Mastodon, worked with First Act on a custom mass-produced nine-string guitar.

Ten-string
B.C.Rich manufacture a ten-string six-course electric guitar known as the Bich, whose radical shape was specifically designed to allow the machine heads for the four secondary strings to be positioned on the body, avoiding the head-heaviness of many electric twelve-string guitars. However many players bought it for the body shape or electrics and simply removed the extra strings. The company recognized this and released six-string models of the Bich, but ten-string models also remain in production.

In October 2008, a ten-string electric jazz guitar by Mike Shishkov was demonstrated at the 3rd International Ten String Guitar Festival. This instrument was based on the ten-string extended-range classical guitar.

Twelve-string
Twelve string electric guitars feature six pairs of strings, usually with each pair tuned to the same note. The extra E, A, D, and G strings add a note one octave above, and the extra B and E strings are in unison. The pairs of strings are played together as one, so the technique and tuning are the same as a conventional guitar, although creating a much fuller tone. They are used almost solely to play harmony and rhythm. They are relatively common in folk rock music. Lead Belly is the folk artist most identified with the twelve-string guitar, usually acoustic with a pickup.

George Harrison of The Beatles and Roger McGuinn of The Byrds brought the electric twelve-string to notability in rock and roll. During the Beatles' first trip to the US, in February 1964, Harrison received a new "360/12" model guitar from the Rickenbacker company, a 12-string electric made to look onstage like a 6-string. He began using the 360 in the studio on Lennon's "You Can't Do That" and other songs. Roger McGuinn began using electric 12-string guitars to create the jangly sound of The Byrds. Another notable guitarist to utilize electric 12-string guitars is Jimmy Page, the guitarist with hard rock-heavy metal and rock group Led Zeppelin.

3rd bridge
The 3rd bridge guitar is an electric prepared guitar with an additional 3rd bridge. This can be a normal guitar with for instance a screwdriver placed under the strings, but can also be a custom made instrument. Lee Ranaldo of Sonic Youth plays with a 3rd bridge.

Double neck guitar
Double neck (or, less commonly, "twin-neck") guitars enable guitarists to play guitar and bass guitar or, more commonly, a six-string and twelve-string. An early user was John McLaughlin, but the double-neck guitar was popularized by Jimmy Page, who used a custom-made Gibson EDS-1275 to perform the "Stairway to Heaven" and "The Song Remains the Same", although "Stairway to Heaven" was actually recorded using a Fender Telecaster. Don Felder of the Eagles also used the Gibson EDS-1275 during the Hotel California tour. Muse guitarist and vocalist Matthew Bellamy uses a silver Manson Double Neck on his bands' The Resistance Tour.

Popular music
Popular music and rock groups often use the electric guitar in two roles: as a rhythm guitar which provides the chord sequence or "progression" and sets out the "beat" (as part of a rhythm section), and a lead guitar, which is used to perform melody lines, melodic instrumental fill passages, and guitar solos. In some rock or metal bands with two guitarists, the two performers may perform as a guitar tandem, and trade off the lead guitar and rhythm guitar roles. In bands with a single guitarist, the guitarist may switch between these two roles, playing chords to accompany the singer's lyrics, and then playing a guitar solo in the middle of the song.

In the most commercially available and consumed pop and rock genres, electric guitars tend to dominate their acoustic cousins in both the recording studio and the live venue, especially in the "harder" genres such as heavy metal and hard rock. However the acoustic guitar remains a popular choice in country, western and especially bluegrass music, and it is widely used in folk music.

Jazz and jazz fusion
Jazz guitar playing styles include rhythm guitar-style "comping" (accompanying) with jazz chord voicings (and in some cases, walking basslines) and "blowing" (improvising solos) over jazz chord progressions with jazz-style phrasing and ornaments. The accompanying style for electric guitar in most jazz styles differs from the way chordal instruments accompany in many popular styles of music. In rock and pop, the rhythm guitarist usually performs the chords in rhythmic fashion which sets out the beat of a tune. In contrast, in many modern jazz styles, the guitarist plays much more sparsely, intermingling periodic chords and delicate voicings into pauses in the melody or solo. Jazz chord voicings are usually rootless and emphasize the 3rd and 7th notes of the chord.

When jazz guitar players improvise, they use the scales, modes, and arpeggios associated with the chords in a tune's chord progression. Jazz guitarists have to learn how to use scales (whole tone scale, chromatic scale, etc.) to solo over chord progressions. Jazz guitar improvising is not merely the recitation of jazz scales and rapid arpeggios. Jazz guitarists often try to imbue their melodic phrasing with the sense of natural breathing and legato phrasing used by horn players such as saxophone players. As well, a jazz guitarists' solo improvisations have to have a rhythmic drive and "time feel" that creates a sense of "swing" and "groove".

Most jazz guitarists play hollow body instruments, but solid body guitars are also used. Hollow body instruments were the first guitars used in jazz in the 1930s and 1940s. During the 1970s jazz fusion era, many jazz guitarists switched to the solid body guitars that dominated the rock world.

Contemporary classical music
Until the 1950s, the acoustic, nylon-stringed classical guitar was the only type of guitar favored by classical, or art music composers. In the 1950s a few contemporary classical composers began to use the electric guitar in their compositions. Examples of such works include Karlheinz Stockhausen's Gruppen (1955–57); Donald Erb's String Trio (1966), Morton Feldman's The Possibility of a New Work for Electric Guitar (1966); George Crumb's Songs, Drones, and Refrains of Death (1968); Hans Werner Henze's Versuch über Schweine (1968); Francis Thorne's Sonar Plexus (1968) and Liebesrock (1968–69), Michael Tippett's The Knot Garden (1965–70); Leonard Bernstein's MASS (1971) and Slava! (1977); Louis Andriessen's De Staat (1972–76); Steve Reich's Electric Counterpoint (1987), Arvo Pärt's Miserere (1989/92), and countless works composed for the quintet of Ástor Piazzolla. Alfred Schnittke also used electric guitar in several works, like the "Requiem", "Concerto Grosso N°2" and "Symphony N°1".

In the 1980s and 1990s, a growing number of composers (many of them composer-performers who had grown up playing the instrument in rock bands) began writing contemporary classical music for the electric guitar. These include Shawn Lane, Steven Mackey, Nick Didkovsky, Scott Johnson, Lois V Vierk, Tim Brady, Tristan Murail, John Rogers, and Randall Woolf.

Yngwie Malmsteen released his Concerto Suite for Electric Guitar and Orchestra in 1998, and Steve Vai released a double-live CD entitled Sound Theories, of his work with the Netherlands Metropole Orchestra in June 2007. The American composers Rhys Chatham and Glenn Branca have written "symphonic" works for large ensembles of electric guitars, in some cases numbering up to 100 players, and the instrument is a core member of the Bang on a Can All-Stars (played by Mark Stewart). Still, like many electric and electronic instruments, the electric guitar remains primarily associated with rock and jazz music, rather than with classical compositions and performances. R. Prasanna plays a style of Indian classical music (Carnatic music) on the electric guitar.

In the 21st century, European avant garde composers like Richard Barrett, Fausto Romitelli and Karlheinz Essl used the electric guitar (together with extended playing techniques) in solo pieces or ensemble works. Probably the most ambitious and perhaps significant work to date is Ingwe (2003–2009) by Georges Lentz (written for Australian guitarist Zane Banks), a 60-minute work for solo electric guitar, exploring that composer's existential struggles and taking the instrument into realms previously unknown in a concert music setting.