In this guitar lesson, you’ll learn about drop D tuning, also known as DADGBE, a form of guitar tuning in which the lowest (sixth) string is tuned down (“dropped”) from the usual E of standard tuning by one whole step (2 frets) to D.  It’s a very popular tuning in the genre of metal because it facilitates faster transitions between power chords. 

Here’s a small list of well known songs played in drop D tuning:
• Kashmir - Led Zeppelin
• Everlong - Foo Fighters
• I Miss You - Incubus
• Grace - Jeff Buckley
• Black Hole Sun - Soundgarden
• Dear Prudence - The Beatles
• The Chain - Fleetwood Mac
• Ohio - Neil Young