I just thought I'd clear that up after all of these "definitions" in which I have encountered an unbelievable amount of people who try to pass off their blatantly false pretenses as fact, and are slowly infecting others with their high-horse, holier-than-thou bullshit. Because honestly, with your ridiculous definitions, Beethoven, George Gershwin, and Britney Spears are/was "emo bands."
Now, onto the real definition.
In the early 90s there was a movement in the hardcore genre that came to be known as "Emotive Hardcore," spearheaded by Rites Of Spring. Harder-core-than-thou kids, who swore by Dischord Records a la Minor Threat, actually coined the term "Emo" as something of a put-down for the kids who really liked Rites Of Spring, Indian Summer and this new wave of "Emotive" Hardcore bands. That's right, "Emo" was once not something kids called themselves. The field exploded outwards from there - Level-Plane Records has always been the most famous Emo label. Acts like Yaphet Kotto, I Hate Myself, Saetia, Hot Cross, A Day In Black And White, Funeral Diner, I Would Set Myself On Fire For You, You And I, and hosts of others came in the next decade. Most emo bands have since broken up, but there's still the occasional hold-out (again, the majority of Level-Plane Records' roster has been a procession of emo acts). Like most DIY hardcore/punk of the time, a majority found its way onto vinyl and not much else. Some people consider bands like Fugazi, and later Sunny Day Real Estate, a progression of emo, but personally, I don't quite follow that philosophy.
Often, more recently, this gets intertwined with post-hardcore, and understandably so - that's nothing to make an issue of, since well shit, at least it's close.
Since the late 90s, though, bands have been emerging in the vein of Taking Back Sunday, Dashboard Confessional, and the thousands of their clones. As far as I can tell, some lazy journalist somewhere, writing an article about them, decided "Well, fuck, no one knows what emo is anyways, so I'll call these bands "emo" - sounds more appealing than bubblegum pop rock..." and the spiral continued downwards into the current amalgomation of bands MTV has told everyone is "emo."
Somehow, people decided that "emo" meant "emotional," which is obviously bullshit, as 99% of bands make music to illicit emotion, which would make "emotional" a completely all-encompassing genre from classical to opera to pop to rap.
Hope that helps.
Rites of Spring is emo.
Wear only skinny jeans or old, crappy, tight, cut-up jeans. Wear tight shirts that you can barely get over your head. If after getting dressed you can't breathe and look like a hobo, you've done it right. No shoes but low-top Converse or slip-on Vans are acceptable. Anything out of Hot Topic will do.
Dye your hair with the cheapest, least-convincing black dye you can find. Nothing over 99 cents. Fix it so that you look like you just rolled out of bed then walked through a hurricane and lost a fight with a lawn mower.
Peirce everything you can reach, and put in the largest, ugliest rings you can find.
Dark, thick makeup is key in the emo world. Never leave the house without putting on globs and globs of badly-put-on black eyeliner. Extreme amounts of bright pink eyeshadow is optional.
Now that we've covered the emo look, it's time to teach you to act the part of an emo, so the others won't think of you as a poser.
Flip your hair vigorously every ten seconds. If your neck is broken at the end of the day, good job.
Whine about your pathetic life every chance you get, (twice as much if your parents are divorced) but never reveal that you live in saburbia. If asked where you reside, say something emo like, "The depths of living hell", "The home of sorrow", or some other pussy shit like that.
Always have your MySpace mood set to "apathetic," and make sure to have about 986730865734567349576 pictures of yourself with extremely emo captions that have plenty of X's. It is necessary to be a MySpace whore, and to beg for picture comments in a bulletin every ten minutes.
Only listen to emo bands such as Dashboard Confessional, My Chemical Romance, ect. If there is an extremely popular emo band at your school, say that you like them even if you don't.
Make it widely known that you cut yourself every night with a razorblade while listening to emo music. If ever asked why, say something stupid like, "I cut myself to stay ALIVE! You would NEVER understand!" Then run away crying, even if you are not upset.
Finally, always deny that you are emo. Claim to be scene, goth, or a "non-conformist." But always keep in mind that you are, and always will be, a pussy little emo fag.
Normal kid: Fuck you, emo.
Emo kid: Oh em gee! I'm not emo! I'm SCENE!
Normal kid: What's the difference?
Emo kid: You don't UNDERSTAND! Why does nobody get me!?!?! *Runs away crying and cutting himself, preparing to post this event on his blog.*
NB: Emo does not mean the person cuts themselves, they might but that is not why they're emo.
2) A style. Quite similar from emo to emo but they try to make it quite unique. Some common features of emo's are:
-long hair that covers their eyes
-skinny fit jeans
NB: Not all emo's wear this style and just because you see someone who has one or more of the above features doesn't mean they're emo.
3) A genre of music. Some people find it depressing, but generally emo's listen to it because it describes something that has happened/happening to them perfectly. It's like the band has taken their memories and found the perfect way to describe it.
NB: Just because a band isn't very popular doesn't mean it is emo and some emo music is very cheery and consoling.
2) You see big groups of emo's in town wearing that style, but still managing to look cool and different.
3) Some people say My Chemical Romance is emo and depressing, but they have some cheeryish songs and their lyrics mean something to some emo's.
Grown-up: You want something to cry about, try being $300 in debt, and $500 behind on cable/gas/electric bills. All the while being asked for dollars and ciggarettes by some urban trash on the way to your apartment.