An electric guitar is a guitar that uses the principle of direct electromagnetic induction or piezoelectricity to convert vibrations of its metal strings into electric audio signals. The signal generated by an electric guitar is too weak to drive a loudspeaker, so 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.
Invented in 1931, the electric guitar became a necessity as jazz musicians sought to amplify their sound. Since then, the electric guitar has become the most important instrument in popular music. It has evolved into a stringed musical instrument that is 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.