Many of the controversies surrounding nationalism can be traced back to rival views about what actually constitutes a nation. Most people don't actually ask the question "what is a nation?" because it seems so self evident, but it is often true in the human mind, that which is closest and most "everyday" to us is usually the least known about conceptually. So what is meant by the term nation? well the problem with defining the term is that it contains objective and subjective features.
Objectively nations are cultural entities, groups of people who speak the same language, have the same religion and are bound by a shared past, basically a group of people united politically in some way. Subjectively it means that nations can only be defined by their members. This is what is meant by a psycho-political construct. Nations are nations because the people regard themselves as a nation. They perceive themselves to be a distinct political community. This one point is what differs nations from other collective groups, for example, an ethnic group shares a sense of cultural pride but lacks political aspirations.
But that being said, traditionally nationalism has had two broad definitions. One views a nation purely as a cultural community, and emphasizes importance of ethnic ties and loyalties. The other sees it essentially as a political community, and highlights the significance of civil bonds and allegiances. The idea that the nation is a cultural identity has been described as the primary concept of the nation. Herder says the innate character of a nation is determined by its natural environment, climate and geography which shaped the lifestyle, attitudes, beliefs and creativity of the people. He believed that language was the most important because it expressed a shared history and traditions. It's a natural organic view of the evolution of a nation, that people have a motivation to group together with individuals who shared the same belonging. It's a bottom-up approach in that its believed a culture comes first, then to make it more rational in the modern world a political tie is then added.
The idea that nations are essentially political entities emphasizes civic loyalties and political allegiances rather then cultural identity. The nation is thus a group of people who are bound together primarily by shared citizenship regardless of cultural ties. The argument is that a belief in a historical continuity and cultural purity was a myth and created by nationalism itself. They argue that a distinctive language passed down from generation to generation is questionable since our language changes generation to generation and only adapts to the present environment for communicative needs. Also since nations are so large people can only meet a portion of the people they share a nation with so how have they come together in cultural unity? it's an irrational thought. It nations exist, they are fictional images communicated by mass media and education as a process of political socialization. From the perspective of Marxism, nationalism is a device through which the ruling class counters the threat of social revolution by ensuring that nationality loyalty is stronger then class loyalty, thus binding the working class to the existing power structure. There are also political nations who have so many cultures that devote to civic liberties is needed, such as US, UK or Australia.