The term identity, which has become a fashionable and overworked concept in social sciences since the mid 1970s, has lost all precise meaning. It replaced the idea of national characters and has become a term for any set of atributes of a social group. As the original meaning of the term - the permanent and unique attributes of an individual or social group- is not accepted anymore, it has been redefined, coming to mean just the opposite of its original meaning: now, all scientist want the term to mean the changing, variable, contradictory characters of a group. Finally, the article states that the use of the term identity in the mark of library activities should be avoided, as it goes against the accepted goals of libraries, which must promote cultural diversity and the contact with all the cultural forms and creations within the country and in the world.