Nation states arise from a combination of cultural and political factors. A nation is defined by shared characteristics like language, religion, or ethnicity, while a state is a political territory with institutions that govern and enforce rules over its population. A nation state unites a cultural nation within the boundaries of a single state. In the 19th century, nationalism and the idea that each nation deserves its own state led many European countries to align their borders along cultural lines. However, not all modern states are uni-national, as some contain multiple nations or cultural groups.