Standard Tuning(E A D G B E)
This is how a guitar is normally tuned.
Open E Tuning (E B E G# B E) The A and D string have to go up one step, the G string a half a step.
This tuning was often used by Robert Johnson and other bluesman for slide guitar.
The tuning is basicaly the same as Open D Tuning just 1 step higher.
If you are worried about to much tension on your guitars neck,
Try to use a kapodaster on the first or second fret before you use the tuner.
Open D Tuning (D A D F# A D) This is next to the Open G Tuning one of the most popular open tunings,
and has been used by many many Mississippi Delta bluesman.
This tuning doesn't put a lot of tension on the neck and gives you
a warm sound with a lot of bottom.
Open A Tuning (E A E A C# E) This can be seen as the higher version of the Open G Tuning,
all the note are one step higher.
This tuning can put a lot of tension on your neck, try the trick with the kapo as
discribed in the Open E Tuning.
Open G Tuning (D G D G B D) This is a very popular Open Tunings that is widely used by Bluesman.
This tuning is often refered to as the "Spanish Tuning", as is the previous Open A Tuning.
Keith Richards loves this tuning, if you want to have a cool rolling stonesy sound
tune your guitar like this.
Open Em Tuning (E B E G B E) From Standard Tuning the A and the D string have to be tuned up one full step.
Delta bluesman Nehemiah "Skip" James (1902-1969) used this tuning a lot,
he called it "E minor cross note tuning"
and most of his compositions were based on it. Open C Tuning (C G C G C E) This tuning goes down very low, if you use thin strings the bottom three might
wobble a bit. Apart from that it is a very nice tuning good for the more darker songs.
DADGAD Tuning(D A D G A D)
The DADGAD tuning was invented by the english guitarist Davey Graham.
It is said that he came up with it to play eastern and arabic music.
You can make up nice chords with this one. Play around with it.