Actually, it is a bit of a spectrum disorder, like many other personality disorders, and if youare what is known as "High Functioning" you might come across as kind of stuck up or self absorbed but not much worse. Others are so bad that their self preoccupation bcan be classed as a delusion, and you really DO NOT want to be anywhere near one of those people. They can be actually dangerous. Most diagnosable narcissists lie somewhere in the middle. To make it even more confusing, a lot of other disorders, because of the damage done to the personality at various ages, can present with narsicistic traits. Even normal people, if they feel that their self and the understand ing of their self is threatened, might show transient narcistic behavior in an effort to protect their understanding of their identity. Ever meet a bunch of tired, stressed med school students? Also true of people suffereing for example, depression or mania, for different reasons.

To the young lady who started the thread: Most people who are true narsicists are basically surface, that's it. Nothing to give, but great at taking. They don't see people as people with feelings, just as back drop to the real star of the show, them. Such people spread pain and heart break around them, and once you have seen that in action, I think you would either want to talk to your boyfriend and ask him why he called you that, or punch him. They don't get why it is wrong to hurt others if they benefit. They don't understand why it is wrong to belittle people to the ground just because that person doens't wear the right clothes. everything is someone else's fault if things go wrong.
This is not self esteem, this is a person who cares only about the surface becasue there is nothing else there at all, and he or she assumes this is the same with everyone. The world is only made up of fronts.
More questions? Ah yes, this is bad because these folks regularly hurt others and commit crimes and most folks don't like people who do that.