OK, here it is: you have to understand in Europe some countries were an amagalm of nations with different languages. Keep that in the back burner.
Now: England and France were strong homogeneous countries - no other nation groups there, no other languages, very stable financially, doing well. These are the national states. Pure! Other nations were a mess. Disorganized, struggling in their economies, with lots of different languages and nation groups among them. So, the Germans said, let's imitate England and France and have our own country with only our own people. this is the start of the nationalism. They say Germany for Germans only. Get rid of everyone else. Germans started the nationalism. Example: , there were slavs in Austria, Russian and Poland. So the said, we are going to get together and get away from Austria, Russia and Poland and make our own country. They called that movement Pan-slavism. This is nationalism. Clear as mud? And of course, Austria Russia and Poland did not like that one bit. ya my teacher has a list of ten things for possible causes of ww1 and destruction of Austro-Hungarian empire is one so maybe i should put that instead of the Germany thing or both? he also said economic rivalry - sure because in order to become a great national state like England and France, you have to have the money! And who ever could went to get another part of the world for its own - first come first get. England go India, Holland got Indonesia, French got parts of Africa, Latin america and today's Cambodia and Vietnam. And that;s imperialism. do you see how one leads to the other?
Both, because