"Nationalism" is a devotion to one's nation and one's national identity. Nationalism can be either positive or negative depending upon the context in which it is used.
Positive nationalism encourages pride and devotion to a country. A nation whose people share in aspirations and spirit experience nationalism. A negative form of nationalism is excessive patriotism to the point of chauvinism. Another form of negative nationalism is when a nation puts its interests above the interests of all other nations. If one nation takes a shared resource as its own without regard to other nations that use that resource, that is a negative form of nationalism.