Alright, i'll explain to you the whole emo thing, because its a fucking epidemic at Boston U.
It begins with the music; emo kids go hand in hand with pretentious indie rockers to a point; emo kids latch on to a relatively unheard of band until they make it huge (when the indie rockers start to say "i loved them before they sold out" and move on) and then they get together with their emo friends and cry for no reason. They follow the trends and styles of any given band until a better option rears its ugly head, but it basically means tight gay jeans for dudes coupled with meticulous haircuts that see hours of manufacturing to appear unkempt.
From the music/image comes the attitude; emo kids, like indie rockers, understand the world on a higher, more emotional level than common folk. Normal people apparently push their emotions aside which is the greatest sin known to man, as emotions are the only thing worth paying attention to.
From the attitude comes the fact that emo kids are completely fucking annoying: they usually are brought up in well-off families (the only reason they can afford a $40 ticket to see Death Cab for Cutie) and have very little to complain about.
Basically, the emo movement is a spinoff of the goth kid movement. While the goth kids started listening to Slipknot and Korn and other shitty uninnovative hardcore music, emo kids started listening to Dashboard Confessional and The Get Up Kids; again shitty and uninnovative, but just with a big blubbering pussy.