Emo music is something that is rather ambiguously defined. It can be something that has heavy punk chords and influence such as what we've heard from the Sex Pistols, but it can also be something with soft melodic characteristics like what we've heard from the Cure. This is why emo is such a hard concept to define. It is an expression of emotion in some way.
http://www.emo-corner.com/emo-music/
