A narcissist is a person who thinks about themselves far too much — their face, their talent, their success — and who does not really notice other people. We use the word to show we do not like this. A vain person just likes to look good. A narcissist needs to be the centre, and other people's feelings bounce off them. In everyday talk, people now throw the word at anyone who takes many photos of themselves or who cannot stop boasting; though actually, in careful speech it is heavier than "vain" or "selfish," and doctors mean something more stuck and serious than "likes the mirror." The name comes from Narcissus, a beautiful young man in an old Greek story who fell in love with his own face in the water and could not leave it.