You have probably heard it often used as an insult, joke or something else, but in fact narcissism is one of the types of personality disorders, a mental state in which people have an exaggerated sense of their importance, a deep need for excessive attention and admiration, have troubled relationships and lack of empathy for others. (via MayoClinic)

It should be noted that psychologically, narcissism does not mean self-love, at least not of a genuine or healthy kind. People who suffer from this disorder are in fact in love with an idealized and magnificent image of themselves. They are in love with this image, precisely because it allows them to avoid deep feelings of insecurity. To "keep" the deceptions of this "greatness" requires a lot of work and this is where dysfunctional behaviors begin.

People with this type of disorder tend to blame others. They are overly sensitive and react badly to criticism, disagreement and see all of these as personal attacks. By understanding more about this disorder, you can spot the narcissists in your life, protect yourself from their power games, and set healthy boundaries.

- Strong sense of self-importance

Greatness is the defining characteristic of narcissism. More than arrogance or vanity, greatness is an unrealistic sense of superiority. Narcissists believe they are unique or "special" and can only be understood by other special people. Moreover, they are very good at doing mediocre or ordinary things. They just want to associate with people and places and of a high status. Narcissists also believe that they are better than everyone else and expect to be recognized as such, even though they have done nothing special. They will often exaggerate or lie about their achievements and talents. When talking about work or relationships, all you will hear is how much they contribute, how great they are, and how lucky the people around them are.

- They live in a fantasy world that supports their delusions of grandeur

Since reality does not support their grandiose view of themselves, narcissists live in a world full of fantasy backed by distortion and self-deception. These fantasies protect them from feelings of inner emptiness and shame, so facts and thoughts that contradict the sense of grandeur are ignored or rationalized.

- They need constant praise and admiration

The feeling of superiority of a narcissist is like a balloon that gradually loses air without a steady stream of applause and recognition to keep it inflated. The occasional compliment is not enough. Narcissists need constant nourishment for their ego, so they surround themselves with people who are willing to take care of their obsessive desire for assertion. These relationships are very one-sided. It's all about what the admirer can do to the narcissist, never the other way around, and if there is any interruption or reduction in the admirer's attention and praise, the narcissist treats it as a betrayal.

- The feeling of having excessive rights

Because they consider themselves special, narcissists expect to be treated differently than others. They truly believe that whatever they want, they should get. I expect the people around them to automatically respect every wish and whim they have. If you do not anticipate and meet their every need, then you are useless. And if you have the nerve to oppose the will of a narcissist, prepare for aggression and anger.

- Exploits others without feeling guilty or ashamed

Narcissists never develop the ability to identify with the feelings of others, to put themselves in other people’s shoes. In other words, they lack empathy. In many ways, they see people in their lives as objects, as if they are there to serve their needs. Consequently, they do not think twice about taking advantage of others and achieving their goals. Sometimes this interpersonal exploitation is malicious, but often it is simply inattentive and occurs even without their control or awareness. It is normal for them. Narcissists simply do not think about how their behavior affects others. And if you point it out, they still won’t understand it. The only thing they understand is their needs.

- Often bully and despise others

Narcissists feel threatened whenever they encounter someone who seems to have something more than them, is more famous or more successful. They also feel threatened by people who oppose them in any way. Their defense mechanism is contempt. The only way to neutralize the threat and support their savage ego is to demonstrate to that person how little it means to them, or to go on the offensive with insults, harassment and threats.

Source: Help Guide