The four long-term causes of World War I are often remembered by the acronym M.A.I.N.

Militarism refers to the glorification of military power and the massive arms race between European nations.

A key example of this was the Anglo-German naval race, as Germany sought to build a navy to rival Britain's.

Alliances refer to the complex and rigid system of military alliances that divided Europe into two armed camps.

The two main alliances were the Triple Entente (Britain, France, Russia) and the Triple Alliance (Germany, Austria-Hungary, Italy).

Imperialism refers to the competition among European powers for colonies, resources, and influence around the world, which created intense rivalries.

Nationalism refers to intense pride in one's nation, which could be both a unifying and a divisive force.

A particularly volatile form of nationalism existed in the Balkans (the 'powder keg of Europe'), where Slavic peoples sought independence from Austria-Hungary.

These four underlying causes created a highly tense and unstable situation in Europe by 1914.

The assassination of Archduke Franz Ferdinand was the short-term spark that ignited this 'powder keg.'