http://en.wikipedia.org/wiki/Emo
Emo (an abbreviation of "emotionally-driven Hardcore punk") is a term now broadly used to describe almost any form of guitar-driven alternative rock that expresses emotions beyond traditional punk's limited emotional palette of alienation and rage. It is also used to describe fans of this genre, most commonly teenagers. (e.g., emo kid). The actual term "emo" originated in the mid-1980s D.C. scene, with the band Rites of Spring, as well as bands such as Fugazi, Moss Icon, and Antioch Arrow. The term addressed both the way the band connected with its audience, as well as its tendency to deal more with topics of personal and relationship politics than with the standard themes of rock music.