All citizens of European Union (EU) member states enjoy EU citizenship. It was formally created with the passage of the Maastricht Treaty in 1992, at the same time as the European Union. EU citizenship complements, not replaces, national citizenship.  It provides EU citizens with the rights, freedoms and legal protections under EU law.
EU citizens enjoy freedom of movement, as well as freedom of settlement and employment within the EU. They can freely trade and transport goods, services and capital across EU national borders without restrictions on capital movements or fees.  Citizens have the right to vote in their state of residence and to stand in elections as candidates, as well as to vote for EU elections and to participate in the European Citizenship Initiative.
EU citizenship confers the consular protection of the embassies of other EU member states when a person’s country of nationality is not represented in the embassy or consulate of the foreign country for which they need protection or other types of assistance.  EU citizens have the right to address the European Parliament, the European Ombudsman and EU institutions directly in any EU treaty language, provided that the issues raised are within the competence of that institution. 
EU citizens enjoy the legal protections of EU law, including the EU Charter and Acts and Directives on the protection of personal data, the rights of victims of crime, the prevention and combating of human trafficking, equal pay for equal work, and exemptions in employment. Discrimination based on religion or belief, sexual orientation and age.  EU citizens can directly contact the Office of the European Ombudsman.
“The introduction of a European form of citizenship with clear rights and duties was considered as early as the 1960s”.  EU citizenship was first introduced by the Maastricht Treaty and extended by the Amsterdam Treaty.  Prior to the 1992 Maastricht Treaty, the European Community treaties provided guarantees for the free movement of persons engaged in economic activities, but generally others did not. The 1951 Treaty of Paris established the European Coal and Steel Community, establishing the right to free movement of workers in these industries, and the 1957 Treaty of Rome provided for the free movement of workers and services.
However, the interpretation of treaty provisions by the European Court of Justice has not a narrow economic purpose, but a broader social and economic purpose.  In the Levin case, the Court held that “freedom of employment is important, not only as a means of creating a single market for the economies of member states, but also as a worker’s right to raise his or her standard of living”.  According to the European Court of Justice case law, a worker’s right to free movement applies regardless of the purpose of the worker’s employment abroad, part-time and full-time employment, and whether the worker requires additional finances from the Member State to which he moved aid.  Since the European Court of Justice held that recipients of services have the right to free movement under the treaty, and that this criterion is easily met, in practice, the nationals of each EU country are in another member state, whether or not they are engaged in economic activities. activities, have a right to non-discrimination under Article 12 of the Treaty on the European Community even before the Maastricht Treaty. 
In the Martinez Sala case, the European Court of Justice held that the Citizenship Clause provided a substantive right to equal treatment, as was already conferred by trade union law. The Baumbast case later established that the right to equal treatment applies equally to economically active and economically inactive citizens. Despite these broad interpretations, the landmark Dano case, which combined standards of freedom of movement and equal treatment, said they were interdependent and subsequently limited the scope of Martinez Sala.