Emotional Post Hardcore-hardcore punk played on the minor keys (thats sad keys to you none musical folks!) with a poor rhythm section whiney vocals integrated with harsh screams singing emotional/introspective lyrics.
Has been around since the mid 1980's
The nerdy 'emo' kids are called:fashioncore they dont listen to emo they listen to bands like My Chemical Romance and they are the ones that cry about ex girlfreinds
Emo: Fugazi, Rites of Spring, Jawbreaker, Embrace, Mineral, Moss Icon, City Of Caterpillar all bands on Dischordwww.dischord.com
or Jade Tree Recordswww.jadetree.com
Not Emo: Taking Back Sunday, My Chemical Romance, Hawthorne Heights, Dashboard Confessional, Bright Eyes, Matchbook Romance etc (in general these bands are reffered to as shitcore or wannabemo-soft-shitcore-rock