Emo is ONLY an insult given by Punks, directed towards the avid fans of Emotive Hardcore Punk & the genre itself. Emotive Hardcore Punk started in the mid/early 80's; with Hardcore Punk bands that added more emotional lyrics to their songs. Since they did this, they were no longer considered Hardcore Punk.
Emotive is essentially watered down Hardcore Punk. That being said; Emotive is still Punk. It's still a sub-genre of Hardcore Punk. They still follow the same DIY ethics as Punks, & still have the same mindset.
The most noted bands to take this form of Hardcore Punk in a new direction was; Embrace & Rites Of Spring. Ian MacKaye the lead singer of Embrace; famous for the Hardcore Punk band Minor Threat, the creation of the subculture Straight Edge, & Dischord Records. Guy Picciotto the lead singer of Rites Of Spring; famous for the Emotive band Fugazi & creator of Emotive itself. (Arguably) Started the genre in the mid '80's.
Emotive in the 80's resembled it's parent genre. In the '90's it took a different feel.
Cap'n Jazz & a few other bands took a more Indie feel to their music. Cap'n Jazz with their only album Shmap'n Shmazz; took Emotive from a from a deeply underground Punk sub-genre, to a more widely accepted subset of indie rock. Which is why Emo is widely known, & respected in the Indie subculture.
Skramz (screamo), a sub-genre of Emotive; was Emotive with a more chaotic playing style. The name of the genre is a misnomer. Though the genre often had screaming vocals, it wasn't the focus of the genre. Skramz was just a way of playing more chaotic music, as most Punk was. Skramz started in the early '90's & lives to this day.
Emotive, along with Skramz, were underground genres. With underground labels. They're not widely known, or heard. You won't hear them on the radio, or find them in your local commercialized record store. This is the backbone of all Punk music, & it's sub-genres.
Common misconceptions of Emo; Emo is a style, Emo means Emotional, Emo is depressed, or people who self-mutilate themselves. All these are false! The media has bastardized the genre. In 2003 an article called The Dashboard Confessional Emo. Since this happened, other alike bands have been given the same assumption. You're practically pawns of the media for believing them. It is now widely believed that this style, which is actually FashionXcore a fashion stole from Visual Kei; closely related to J-Rock, which has been played upon by corporations like Hot Topic. They only plan on making money, & don't care what they ruin, or put in it's place.
I've heard recently that Emo died in the '90's. This is also false. Fugazi, a monumental Emotive band that both Ian MacKaye, & Guy Picciotto were both in; were touring & creating records till '01, with their 6th LP. Emotive will still live on with Skramz. In no way is Emotive dead. As long as people still listen to the genre, there will be Emo.
You're not emo unless you either listen to Emotive Hardcore Punk, or you're in an Emotive band. Simple!
I will leave this with some Emotive, Skramz, & some Indie/emo bands: Evergreen, I Hate Myself, Joan Of Arc, Joshua Fit For Battle, Mass Movement Of The Moth, Violent Breakfast, Suis La Lune, Circle Takes The Square, Saetia, Raein, Get Fucked, American Football, Jeromes Dream, Yaphet Kotto, Neil Perry, Amber Inn, Funeral Diner, Harriet The Spy, Cowboys Are Indians, City Of Caterpillar, etc etc...
A: Ready for that emo concert tonight?
B: Hell yeah man, it's going to be great.