Drop D tuning
The Drop D tuning is perhaps the most common altered tuning and it's a handy one since only one string is changed.
It can be used in many styles and is especially popular in hard rock and one reason for that is that it allows power chords to be played by placing a single finger over the same fret. Drop D tuning should not be confused with Open D tuning.
Here is how you tune the guitar: DADGBE. Compared to standard tuning, the only difference is that you tune down the lowest (thickest) string a whole step, from E to D. Now you have a guitar that delivers more bass in the sound; perfect for some rock styles as already mention, but there are other possibilities as well. There is also the Double Drop D.
Power chords
There are two alternatives for playing power chords in this tuning. Here are examples of chords with both shapes, which obviously are movable.
D5
F5
A5
C5
D5 (XII)
D5
E5
G5
Comments
The popularity of this tuning depends much on the many heavy and cool riffs that can be easily created by using power chords in alternation with the open D5. A video that demonstrates this. Here's a chord progressions, meant to play raw and in a fast tempo:
D5 - D5(XII) - D5 - C5 - D5(XII) - D5 - C5 - C#5 - D5(XII)
Chords with alternative bass notes
Power chords with alternative bass notes and suspended chords alike are very useful and can be used together with the regular power chords presented above.
F#5/D
F#sus/B
Dsus/G
Esus/A
Song example
The song "Everlong" by Foo Fighters uses three of the above chords in the verses:
F#5/D - F#sus/B - Dsus/G - F#sus/B
Open chords
Since only the lowest string differs from standard tuning, many open chords could be played just as normal. Although, rich sounds can be found by include the open strings, especially for D chords. For chords that otherwise use the sixth string, such as E and G, there are some new conditions (E major is by the way not very common in songs using this tuning).
D
Dmadd2
Em
A/D
G/D
C/D
Comments
Em can also be played by using three fingers or the thumb. An alternative way to play Em is xx1000. The G chord can also be played as 020003.
Additional open chords in Drop D:
Dm: 000231
Dmaj7: 000222
Dm7: 000565
Dm13: 033000
E: 222100 / XX2100
E7: 220100
Em7: 220000
Em9: 220002
Emadd4: 202000
Fmaj13/D: 003210
F#m: XX4222
F#m11(b9): 402000
G: 5X0003 / 550003
Gmaj7/D: 020002
G6/D: 020030
G6/9: 500000
Bm: X2443X
A: X02220
A11/D: 002423
Using shapes around the middle open strings
The 3rd, 4th and 5th strings played open forms a D chord. You can create shapes around these three open strings, some examples are:
Gsus2: 500035
G6/A: 700057
G9sus4/F: 300013
Blues chords
In Drop D tuning, some new opportunities for blues guitar turns up. These are some chord ideas for playing blues in the key of D.
D7
D7 (II)
D7 (III)
G9/D
A7/D
Comments
The shape for G9/D will result in G7/D played as XX0001.
Barre chords
The conditions for barre chords changes when the lowest string is included.
Common barre chords that are played differently:
F: 333211
F7: 331211
F6: 3X3211
Fsus2: 333563
Fm: 313111
Fm7: 331111
Chord progressions
Progressions in this specific tuning:
D - C/D - A/D
Dmadd2 - Fmaj13/D - C/D
Aadd9 (777600) - D6add9 (12 12 12 11 0 0) - G6 (555400) - Aadd9/Gb (444200) - Esus4/D (000200)
More progressions can be found in the ebook referred to below.
Although Drop D are especially suited for playing in D major key it should not stopping you from playing in other keys as well, for which new ideas can emerge. It expands the bass register and can sound very cool.
If you want to go more into depth of this particular guitar tuning, see the Essential Chords in Drop D Tuning ebook with over 100 chord diagrams.
This was an introduction about chords and playing ideas in the Drop D tuning, see also Drop C tuning.