This is a pretty straightforward, yet awesome song. Song is in Standard Tuning.

Each chord represents one measure of playing.

Verse progression:
G D C G (x2)
D G C D
G D C G

Chorus progression:
D G C G (x2)

Extended chorus progression:
D G C G (x2)
C G 
C C
G G

Song structure:
Verse
Verse
Chorus
Verse (instrumental)
Verse
Chorus
Extended Chorus