Contrary to popular belief, "emo" is not short for "emotional" and it doesn't necessarily imply that someone is sensitive, shy, or introverted, even though the term has morphed and is now used in this way. For example, my friend's dog is overly sensitive so they nicknamed him emo.
Rather the term "emo" originated from a style of rock music characterized by melodic musicianship and expressive, confessional lyrics. It originated in the mid-1980s hardcore punk movement of Washington, D.C., where it was known as "emotional hardcore" or "emocore" which was pioneered by bands like Rites of Spring and Embrace.
Generally emo is tied to both music and fashion as well as the emo subculture, which is stereotyped as tight jeans on males and females alike, long bangs brushed to one side of the face or over one or both eyes, dyed black, straight hair, tight short-sleeved t-shirts with names of emo bands on them, studded belts, belt buckles, canvas sneakers, skate shoes, or other black shoes, and in some cases thick, black horn-rimmed glasses.
You often see this term online and as the style spread to younger teenagers, it became associated with depression, self-injury, and suicide. Some millennials describe "being emo" like "being a goth" only much less dark and much more Harry Potter with the differences being emos hate themselves whereas goths hate everyone; emos want to kill themselves whereas goths want to kill everyone.
For example, as seen on Wikipedia: emo music has been blamed for the suicide by hanging of Hannah Bond by both the coroner at the inquest into her death and her mother, Heather Bond, after it was claimed that emo music glamorized suicide and her apparent obsession with My Chemical Romance was said to be linked to her suicide. The inquest heard that she was part of an Internet "emo" cult and her Bebo page contained an image of an 'emo girl' with bloody wrists. It also heard that she had discussed the "glamor" of hanging online and had explained to her parents that her self harming was an "emo initiation ceremony". Heather Bond criticized emo fashion, saying: "There are 'emo' websites that show pink teddies hanging themselves." After the verdict was reported in a popular music magazine, fans of emo music contacted the magazine to defend against accusations that it promotes self harm and suicide.
NetLingo Classification: Online Jargon