A guitar controller is a video game controller

Game controller

A game controller is a device used with games or entertainment systems used to control a playable character or object, or otherwise provide input in a computer game. A controller is typically connected to a game console or computer by means of a wire, cord or nowadays, by means of wireless connection...

 designed to simulate the playing of the guitar

Guitar

The guitar is a plucked string instrument, usually played with fingers or a pick. The guitar consists of a body with a rigid neck to which the strings, generally six in number, are attached. Guitars are traditionally constructed of various woods and strung with animal gut or, more recently, with...

, a string

String instrument

A string instrument is a musical instrument that produces sound by means of vibrating strings. In the Hornbostel-Sachs scheme of musical instrument classification, used in organology, they are called chordophones...

 musical instrument

Musical instrument

A musical instrument is a device created or adapted for the purpose of making musical sounds. In principle, any object that produces sound can serve as a musical instrument—it is through purpose that the object becomes a musical instrument. The history of musical instruments dates back to the...

. Guitar controllers are often used for music games such as UmJammer Lammy: NOW!, GuitarFreaks

GuitarFreaks

is a music video game series produced by Konami. The player uses a controller to simulate the playing of an electric guitar. The game consists of music predominantly from rock and roll and J-Pop genres, and is now in its 19th version, GuitarFreaks V8, which was released in March 28, 2011...

, Guitar Hero

Guitar Hero

Guitar Hero is a music video game developed by Harmonix Music Systems and published by RedOctane for the PlayStation 2 video game console. It is the first entry in the Guitar Hero series. Guitar Hero was released on November 8, 2005 in North America, April 7, 2006 in Europe and June 15, 2006 in...

, and the Rock Band

Rock Band

Rock Band is a music video game developed by Harmonix Music Systems, published by MTV Games and Electronic Arts. It is the first title in the Rock Band series. The PlayStation 3 and Xbox 360 versions were released in the United States on November 20, 2007, while the PlayStation 2 version was...

series. The controllers are played by holding down a colored fret button that matches a colored, on-screen note, while pressing the strum bar as the note passes through the target. The controllers also feature a whammy bar, which is used to bend notes and collect each game's equivalent of bonus energy. Different games and models of controllers have introduced additional features, such as effects switches, additional fret buttons, and fret touch pads. The fret buttons are colored usually in the order of (from lowest to highest pitch) green, red, yellow, blue, and orange.

Implementation as game controllers

A Guitar controller is almost always an adaption of existing controller technologies for a given console—all features of the guitar are implemented using features found on a standard game controller. Generally speaking the following apply:

• Fret Buttons are implemented as the standard action buttons on the controller- for example, the buttons on a Guitar Controller for the Xbox 360 map to the A, B, X, Y and Left Shoulder buttons on the standard Xbox controller.
• The whammy bar is implemented as an axis
• The meta buttons (start, select, back) map directly to their standard controller counterparts.

Other, vendor-specific features can be implemented using standard controls, or combinations of them- for example, the solo bar on a Rock band guitar controller is implemented using the same controller buttons as the main fret buttons, plus an additional modifier key, whereas the Slide Bar from recent versions of Guitar Hero is simply another axis.

The "tilt" function is also usually mapped to an axis.

Use as a musical instrument

Numerous attempts have been made to adapt Guitar Controllers for use as legitimate musical instruments. These attempts range from simple solutions that output a single note or sound for each button on the controller, to more complicated applications, such as MIDItar Hero

MIDItarHero

Miditar hero is a program made in Max/MSP to allow a Guitar controller to be used as a midi controller. Miditar hero is compatible with Windows XP/Vista and Mac OSX.-Controller Compatibility:...

 and Armchair Guitarist that attempt to fully adapt the controller to use as an instrument, with a wide range of notes and playing styles.