The Extended-Range Bass, ("ERB") as a term, refers to an electric bass guitar with more range (usually meaning more strings, but sometimes additional frets are added for more range) than the "standard" 4-string bass guitar. In practical usage, however, the term is often applied more to basses with more than 5 strings, including 6, 7, 8, 9, 10, 11, and even 12-string basses. Bass guitars tuned one octave lower than a "standard" four-string instrument are also considered an extended-range bass. "Extended range-bass" does not refer to basses with doubled or tripled courses of octave strings.