Nationalism is defined as loyalty to one's nation rather than to an individual leader. It emerged in the Middle Ages and grew with the Industrial Revolution as empires broke up and competition increased between nations in areas like sports, technology, and colonies. Methods used to create nationalism included establishing a shared history through textbooks, folk stories, and public schools, as well as creating national dictionaries, anthems, propaganda, and appealing to militarism and nationalism during wars. While nationalism can foster unity, it can also have negative outcomes.