GUITAR TUNING (from low to high/thickest to thinnest)

Standard 6 string :  E A D G B E

Some alternative tunings :  D G D G B D ("slack key"), D A D F# A D, E B E G# B E, D G D G C D ("saw mill"),...etc.

12 string : E+E (octave) A+A (octave) D+D (octave) G+G (octave)  B+B (unison) E +E (unison)

7 string guitar :  B E A D G B E

Check out the following sample guitar lessons