For acoustic and electric guitar, the standard tuning is “E,A,D,G,B,E” (from lowest string to highest). For the electric bass, the standard tuning is “E,A,D,G”. Altered tunings are used to obtain lower notes (e.g. drop D tuning, in which the low E string is lowered to a D), facilitate the playing of slide guitar, or to allow the playing of “open” chords that are not possible in standard tuning.