Revision with unchanged content. The meaning of the European Citizenship is not easy to explain. We know the meaning of the words, but we might not know how many-sided the implications are inside them. After a brief historical overview of the birth of the concept, special attention will be given to particular rights thereof, concentrating on the two most important ones; namely the principle of free movement and the principle of equal treatment. These rights influence the life of more than 375 million people living in the European Union. It will show and analyze several cases of the European Court of Justice – proving how European Citizenship can change the life of individual people in different countries. This paper is addressed firstly to people working with law, law students, lawyers, mainly to make it easier for them to understand the developments the concept has undergone, and secondly to every person living in the European Union to encourage them to turn to the European Court of Justice in case they feel that they were mistrusted or misjudged previously.