A nation state is the one in which a majority of its citizens,and not only the rulers,come to develop a sense of collective identity and a shared history or descent.
Features of a nation state are:
1.People living in a nation state enjoy equal rights under a constitution.
2.There is a common national flag.
3.There are no internal custom duties and a common national currency is there.
In simple words,we may say that formation of a nation state means unification.