Probably one of the most, if not the most recognisable guitar riffs in rock music history. The opening riff is played in two-string chords made up of root-plus-forth, rather than power chords made up of the usual root-plus-fifth. Its popularity has not ceased to grow in the entertainment industry, featuring on numerous movie soundtracks and covered by a plethora of groups.
this song at iTunes or Amazon. The official band site is here.