Jazz guitarists are guitarists who play jazz using an approach to chords, melodies, and improvised solo lines which is called jazz guitar playing. The guitar has fulfilled the roles of accompanist (rhythm guitar) and soloist in small and large ensembles and also as an unaccompanied solo instrument. Amplification created possibilities for the guitar. Charlie Christian was the first to explore these possibilities. Although his career was brief, it was influential enough for critics to divide the history of jazz guitar into pre- and post-Christian eras.