There are other ways to tune your guitar, depending on what type of music you are play and how you want it to sound: D A D G A D
There is a whole subculture of guitarists who play exclusively in DADGAD tuning. Jimmy Page and other rock guitarists have used DADGAD .
D D G G B D
Keith Richards has used this alternate tuning, and has written many classic Rolling Stones riffs in open G. Many slide players also prefer open G, which is tuned to a G major chord.
Although this alternate tuning has been around for a long time, the Seattle grunge movement in the early 1990’s brought about it’s popularity. Drop D tuning was used extensively by bands like Nirvana, partly because it made playing power chords with one finger possible.
Another somewhat unusual alternate tuning, low C tuning is more often used in Celtic music. You can create some very unique sounds with this one.
Slightly more obscure, open C is tuned to a C major chord, and utilizes a very low sixth string to give the guitar a big, full sound.
When the open strings are strummed in this alternate tuning, the sound of a D major chord is produced. This has made this tuning a favorite of slide players, who can simply lay their slide straight across one fret to play chords.
Keith Richards has always loved this alternate tuning, and has written many classic Rolling Stones riffs in open G. Many slide players also prefer open G, which is tuned to a G major chord.