In drop D, the three open bass strings form a D5 power chord. Other fifth chords are made when barred with the index finger of the fretting hand shifted up the fretboard. Drop D tuning is frequently used in heavy metal and its various subgenres, as guitarists in these styles often need fast transitions between power chords. Drop D is also used in metal because it adds two lower semitones to the bass range of the rhythm guitar, which adds two more low-range power chords (Eb and D) and enables a “heavier”, deeper sound. The tuning has also been used in many other styles of music, including blues, country, folk, and classical. Due to its similarity to standard tuning, drop D is recognised as a useful introduction to alternative tunings, leading logically to an exploration of DADGAD, open D and drop D drop G (in which both the 5th and 6th strings are dropped a tone) tunings.