I think you are confusing NuMetal (Korn,Limp Bizkit) with Emo.
EMO is emotionally driven hardcore (or softcore) PUNK. It began with bands like: Rites of Spring, Hüsker Dü, Fugazi, Jimmy Eat World, and is now bands like: Dashboard Confessional, The Used, Coheed and Cambria, Poison the Well, My Chemical Romance, Hawthorne Heights
Its screaming,melodramatic,moody, soul-searching lyrics, sometimes whiney, nerdy dressing, unwashed messy hair combed forward covering most of your face, tattoos & ear plugs earrings......
I saw this definition,its funny, and it fits -- "Mature" music made by cigarette-puffing ex-straightedgers. Heavy on soul-searching, hard to mosh to."