There are allot of different stereotypes around being emo, most people tend to think emos are emotional whiny people who feel like they are alone in the world. This couldn't be farther from the truth most of the time, allot of people just like the emo style and adopt it. I have friends who are emo who are the happiest guys I know.
Being emo dosent have to entail cutting or hurting yourself but sometimes it does, everybody is different and in being so those people will make their own definitions of what being emo is.