7-string electric guitars extend the standard range with a low B string, opening new creative possibilities in progressive metal, jazz, and fusion. Pioneered by Ibanez with the Universe series, other key manufacturers include Jackson, Schecter, and Kiesel. These guitars allow for extended chord voicings and aggressive riffing, making them a staple in djent and modern metal. While requiring an adjustment in technique, 7-strings are invaluable for musicians looking to push beyond traditional guitar ranges.