A Short History of Emo
Emo is a style of hardcore that emerged in the mid-80s when bands playing hardcore punk got tired of the same old sounds, and decided to try something new. What came of this was emocore. Rites of Spring (which formed in 1984 by Guy Picciotto, Eddie Janney, Brendan Canty, and Michael Fellows) are hailed as the first ever emocore band. They played something similar to DC hardcore that focused more on emotional release, rather than political and social themes like most hardcore of the time did. 1985 was dubbed the "Revolution Summer," when many emocore-style bands started forming.
Although there were hints of emo (the Hated, mainly) before 1986, many believe that Moss Icon were the frist emo band. They took Rites of Springs' emotive hardcore and focused more on the emotion aspect. Moss Icon (Tonie Joy, Marcus Laurence, Jon Vance, and Monica Digalleonardo) added talented and intricate guitar work into the mix, as well as a focus on loud/soft dynamics, and full on screaming.
In the early-90s Emo started to change somewhat, with bands using octave chords and a more intense vocal approach. The loud/soft dynamic was still there, and it played an even bigger part than it did in earlier emo. Bands like Indian Summer, Navio Forge, Native Nod, and Embassy used the dynamic along with intricate guitar work and poetic lyrics to create beautiful, serene emotive hardcore. Emo bands started springing up all over America in the early- to mid-90s, and this was considered the salad day of emo.
Over in San Diego, however, something much more intense was in it's beginnings: Hardcore Emo. In 1991, Heroin kick-started hardcore emo with it's over-the-top abrasive hardcore sound. They played extremely fast and relentless chaotic emo with vocal-chord shredding screams and distorted guitar and bass. In the San Diego area, bands like Honeywell and Swing Kids played this style, and many bands incorporated their own elements, making it rather diverse.
Some say emo died in 96 or so, but I don't think this is true. There are still emo bands out there, like City of Caterpillar, Calvary, Yaphet Kotto, and Neil Perry. Although it has died down a lot and changed a bit since the early- and mid-90s, emo still exists. Sadly, the term emo has been horribly disfigured by Mtv and the radio. Dashboard Confessional, Sunny Day Real Estate, Saves the Day, Thursday, etc. stray so far from the emo sound that there is little or no connection whatsoever. I still can't figure out why and when people started calling these bands emo, but they surely aren't any part of the genre.