But first..
What is an emo?
Anybody who's emo is a f*****t, especially if they have a uterus. Emo males have been known to have no d**k due to the tight pants they wear.
Although it is often mistaken as being short for "emotional," emo was originally the abbreviation for a type of music known as "emotive hardcore." Emo music performances were extremely dramatic, typically including lead singers falling to their knees and screaming or crying. Because traditional hardcore contained a lot less whining and a lot more beating people up, "emo" soon became a taunting nickname used by punks to insult other, more sensitive members of the hardcore scene. The "emotive" part of emotive hardcore is that it attempts to authentically convey raw human emotion.
Conclusive scientific evidence suggests that emos are more hated than both blacks, Jews, and Lath combined, and for good reason, too: they produce over 9000 doses of deadly anti-lulz per year.

The current incarnation of emo has basically replaced all other teenage culture as the dominant one. The slightly faded "vintage" clothing and track suits are available at any mall and often displayed in tandem with the most mainstream wares. Because the accouterments and garb are very easy and cheap to obtain, it makes the style accessible to anyone. In earlier times emo was a generally male-dominated subculture with very few females observed at shows and events. Now, however, due to the ease of obtainment of the requisite style items, many females have become involved in the subculture. Please see the above photo for an illustration of a typical specimen. There may be no easily discernible differences between the standard teenager and someone involved in the emo scene.
Often, participants are referred to as "emo kids," just "kids," "emofags," just "fags," or any combination of these. Rednecks often refer to the participants simply as "wrist-cuttin' hippies". Normal people often say that "Emo" is short for "stupid self-absorbed attention whore who listens to bad music". Everyone else calls them "failures at life". However, some argue that those who constantly complain at emos are a bunch of hypocrites, as they come of being at least twice as angsty and whiny themselves.
Anybody agree? Of course. They pissing me off, beyond words.
Also, emo bands are as follows. If you like more than one of these guys, you're emo. Dashboard Confessional, Hawthorn Heights, Evanescence, My Chemical Romance, 30 Seconds to Mars, Staind, and (the father of all crap) Fall Out Boy.
And, some emo pics.

