Citizenship is membership in a political community (originally a city or town but now usually a country) and carries with it rights to political participation; a person having such membership is a citizen. It is largely coterminous with nationality, although it is possible to have a nationality without being a citizen (i.e., be legally subject to a state and entitled to its protection without having rights of political participation in it); it is also possible to have political rights without being a national of a state.

See nationality for further discussion of the properties of national citizenship and how it can be acquired. You can also read the summary of European Citizenship Laws.

Citizenship often also implies working towards the betterment of one's community through participation, volunteer work, and efforts to improve life for all citizens. In this vein, schools in England provide lessons in citizenship; in Wales the model used is Personal and Social Education.

Citizenship, which is explained above, is the political rights of an individual within a society. Thus, you can have a citizenship from one country and be a national of another country. One example might be as follows: A Cuban-American might be considered a national of Cuba due to his being born there, but he could also become an American citizen through naturalization. Nationality most often derives from place of birth (i.e. jus soli) and, in some cases, ethnicity (i.e. jus sanguinis). Citizenship derives from a legal relationship with a state. Nationality can be lost, as in denaturalization, and gained, as in naturalization.

http://en.wikipedia.org/wiki/Citizenship