World War I was caused by many factors. Some of these include: the assassination of Franz Ferdinand, Militarism, Nationalism, Alliances, Imperialism, and the breakdown of the European treaty system and the 19th century balance of power.
There were many effects of the Great War. Some were more positive than others. Some of these effects include: the separation of nations, creating new countries such as Turkey, Germany was blamed for the war and had to pay reparations, and billions of lives were lost.
We are still experiencing the effects of World War I today. Some modern impacts of the war are: there are more countries in Europe do to the breakdown of some nations such as Russia and Germany, machine guns, poisonous gases, and tanks were introduced, and trench warfare was introduced.