Nationality theory is one of the most important elements of legal system and constructs one of the bases of sovereignty, named as nation. We can define nationality as a legal system that the government defines in order to determine the element of nation. Through this system individuals are subjected to an attibute. Nationality by acquisition and nationality of origin are two classes of it. Nationality by acquisition can be obtained by marriage or acquired from the government. When somebody obtains the capacity for nationality by acquisition, it does not bring about any right for him, but he can only apply for citizenship.

Nationality requisites are classified into: 1. the capacity to have right and 2. the capacity to exercise right. Among the capacities to have citizenship right we investigated residence (duration, features, etc.), qualification (political or criminal record), solvency, and inclination. Personal capacity and language familiarity are two of the capacities to exercise the right that we explained in this work. But sometimes citizenship is acquired without any prerequisites. Among the formalities of nationality acquisition we explained the official process, the time when citizenship is established, etc.

Acquisition of citizenship has collective and individual consequences. We considered the religious status of persons in citizenship process. Civil and political rights are some of the individual consequences. Duties and commitments are also considered.